This is transitions everywhere I can think of them: between scenes, chapters, books, and so on.

1) When using a cliffhanger, consider how long it will be before the audience can see these characters again.

I can see the point of ending a chapter with a cliffhanger, even when the next chapter moves to a different viewpoint character. After all, you want the reader to “read on!” Martin is one author who does this very effectively.
However. (That’s my preferred form of “but” at the moment. You’ll probably be seeing a lot of it during this rant).
A cliffhanger is one of the most transparent forms of a transition. It can annoy your readers instead of engaging them; I’ve heard people complain about Martin for this very reason, and compare the writing of A Song of Ice and Fire, with its frequent cliffhanger transitions, to weekly episodes of a TV show. If you do it too often, it can seem as though you’ve lost the plot, and want to make your audience anxious while you figure out what to do next. If you cliffhang and then don’t go back to the character in danger for 100 pages, or 200, the readers may have forgotten all about the danger and get annoyed at you for dragging them away from someone else with whom they’ve become intimate.
And then there are cliffhangers at the ends of books, which I loathe. I think that each book in a series should pause at a natural resting point, gathering its breath before lunging forward. The world might still be in danger, but it’s just fucking bad manners to leave the reader not knowing if the world will explode on the next page when they don’t have the next page in their hands. It also combines the tendency to annoy your readers and seem transparent, mentioned above, with the knowledge that this time, the wait will be even longer.
The very worst example of a book-ending cliffhanger is when you leave a character hanging between life and death. I’ve read, I think, three books now that ended that way. Each time, I decided I wasn’t reading another of that author’s books, because my anger at being manipulated was stronger than the desire to knew what happened next.

2) Don’t use the “coy” cliffhanger.

This is the one where you end chapter 6 with “Suddenly, he felt an arrow pressed against his neck” and begin chapter 10, the character’s next viewpoint chapter, with “”Ha-ha, got you!” laughed Peter, as he danced in front of Hal and showed off his ice-cube.” The character isn’t really in danger. It’s not a true cliffhanger. It’s the author including an utterly unnecessary scene for the sake of being cute or coy.
To these authors, I say: Look, over there, a good transition!
*Limyaael shoots them with true arrows while their backs are turned*
Stop it. Right the fuck now. Tension and humor don’t go together nearly as well as most authors think they do; you can see this in the nauseatingly stupid cracks that the hero comes up with when a good idea would be to keep his big fat mouth shut and look for an opportunity to escape. If you do humor well, it breaks the tension, destroying the point of having it in the first place. That might be necessary during an extended scene where the characters are cracking mordant jokes in a desperate attempt to keep their mind off of death, but it sucks, it really fucking sucks, as a transition.

3) Try to restrict characters fainting, falling asleep, passing out, and so on to transition past the moments when nothing important is going on.

I’ve done it. You’ve done it. You know this one. The character faints, or falls asleep, or passes out, and when he wakes up, someone explains what’s happened while he was asleep.
I think it can work. I think it’s even plausible when, say, the character is reeling from blood loss and has been on his feet for ten hours, and it wouldn’t make sense for him to summon more god-like strength. What I object to (are you listening, you there in the back row?) is having the character do this at the height of the action.
Tolkien kept doing this. Frodo at the Ford. Pippin on Gandalf’s horse as they raced to Gondor. Pippin at the Battle of the Black Gate. I suspect it wasn’t as annoying as it could have been because the incidents tended to get separated by hundreds of pages, and there werehobbits (Tolkien’s preferred viewpoint characters) awake at a lot of exciting moments, such as when Frodo and Sam finally reach Orodruin. Still, it’s annoying to think about. The author builds up to a fever pitch…and then denies the audience the chance to read about it by having the character drop into darkness, and the viewpoint falling with him.
Used badly, these transitions also have unfortunate implications: that you can’t really think of a way to write the exciting scene, so you’ll just have the character faint and then another character recount it in flashback. Don’t do this. Let the character, and the reader, go through the exciting scene, and then have that person unconscious or ‘near-dead’ or whatever your favorite word is for those few days when they really don’t have to get out of bed, because no one is doing anything interesting.

4) Introduce scene leaps when you can predict the scene that’s going to happen.

Let’s face it: there are some fantasy scenes it’s very hard to write well by now, because we’ve seen all of them so many times we could recite them in our sleep. A particular example is when the hero has been captured, and is left tied up for a time before the leader of his captors shows up. We know he’s sitting in a hard, uncomfortable chair; that he’s looking for something sharp to get the ropes on his hands undone; that he’s probably scared or angry or both, and thinking about his companions left behind on the edge of the camp; and that he’s busily making plans that may or may not come to fruition. The real, true, interesting action starts when the leader shows up, because this leader is different (at least, I really hope he is, and not just the fat sweating buffoon “who moved with odd grace for a large man” that the author could also skip right past, leaving the readers out of nothing important).
Predictable scene? Skip. Line gaps or asterisks or whatever else you use to indicate in-chapter transitions are wonderful things when it comes to these. You don’t bore your readers, you don’t bore yourself, and, if absolutely necessary, you can compress these skipped scenes into mini-flashbacks of a few sentences later, when the hero has some distance from and time to think about them.

5) La-la-la across the landscape. No attacks? No important events? Skip.

The characters may have to spend endless boring miles walking or riding, in which nothing more exciting happens than a bit of rain. It is cruel, cruel I tell you, for an author to make his reader walk or ride with the characters just so that they can admire the author’s absolute lack of skill in description of the landscape.
Tangent: This is one thing that aspiring fantasy authors tend to blame Tolkien for. Pish. At least Tolkien had a) landscape description skills that outmatch what a lot of fantasy authors’ve got and b) the sense to know when he didn’t need to spend pages and pages on a scene. The Fellowship spends two months in Rivendell—something easy to ignore because Tolkien goes skip for a lot of it instead of describing every endless moment in detail. They spend two weeks walking before they get to Caradhras and Moria, but again, in large part,skip; it’s when the crebain show up, the scouting birds of the Shadow, that Tolkien goes into more intense detail. Tolkien has a lot of faults as an author, but those fantasy authors who insist his description of travel “ruined it for everybody” have no one to blame but themselves. /tangent
Admittedly, these transitions are best saved, I think, for between chapters; Chapter 5 ends with the heroes having had a messy, tear-laden confrontation and agreeing to ride on to the city of Therondal together, and Chapter 6 begins with them entering Therondal. It’s much, much easier to say, at the beginning of Chapter 6, “Serai straightened her muscles wearily. She found it hard to believe it had been eleven days of riding, though her back certainly thought so; one day followed another and blurred into one in her mind,” than to give your little scene gap signal and begin the next scene with “Eleven days later…” First, that can seem a cheat. The start of a new chapter at least signals that something momentous happened, since it’s a larger pause than a scene gap. Second, the “Eleven days later…” bit often involves use of an omniscient voice (continued as the heroes pause on a hill and look down, and the omniscient narrator describes Therondal). And most authors are not skilled enough in the omniscient voice to pull this off.

6) Try quiet little scenes as transitions between ones of intense emotion.

One thing that often contributes to melodrama in fantasy is when the author ends one scene where the character’s broken down and cried, and switches to another where the second viewpoint character is tense and in prison. There is no rest for the audience, or, assuming the author writes in a linear fashion, for the writer. She just hurls herself from peak to peak and drags the audience along with her.
I tend to plant my heels when that happens, personally, or put the book down. I want some time to think and absorb the intense emotion. If this is the third or fourth time the author has done this, I might put the book down and not pick it back up. Most authors don’t want that to happen.
Instead, you might want to have the next scene be a humorous bit, or switch to the less tense moment of the characters just entering the enchanted forest, or even show the character reflecting and coming to terms with what just passed. For me, though the last works really well, it’s also really risky. (Sensing a common double-edged theme here?) The author may wander into the sludge of introspection and never emerge again for pages, or, worst of all, not nudge the character on to anything new; she’s just thinking thoughts she’s already thought before, because the experience either wasn’t new or the author isn’t kicking herself out of circular plotting. At some point, your audience gets tired of repetition, and the character saying over and over to herself “Is this action right?” or “Do I really love him?” Try to stay away from that.
Showing an unexpected character introspecting can work wonders, though. Perhaps the tense scene immediately before this was from the viewpoint of the heroine battling a lizard-man who can possess people, and who was trying to make her kill herself so he could take the mystical amulet. But the next, introspective scene is from the viewpoint of her companion who helped her kill the lizard-man, and is reflecting on how close they both came to death. This can show that the people around the heroine have feelings too. /sneak peak of the fleshing-out secondary characters rant.
Get to know the rhythm of the tension in your books. It can’t all be mountains, you know. Mountains take time to climb, and there are valleys. Valleys make excellent transition points.

7) Be careful when intercutting simultaneous tense scenes with each other.

Too many authors think they are Stephen Spielberg. Hell, too many authors think they’re movie directors, period. I don’t know why it’s common knowledge that screen techniques can’t capture much of what goes on in books, but, seemingly, uncommon knowledge that a lot of screen techniques don’t transition well to fiction writing, either.
The most pernicious of these for my money is the panoramic descriptive beginning, where the author thinks he’s a movie camera, but I’ll treat that in the beginning rant. For this point, I mean those authors who think the best way to keep up tension between scenes is leaping away from one every few paragraphs, alighting on a second, then leaping back to the first (or even to a third), a la a movie that alternates between characters inside a burning building and those outside.
You know why that works in movies? Because they don’t need to do set-up. They can give you a glimpse of a face, and you know that face. The visual impact is immediate, in a way that a scene in a book can’t be. Also, movie audiences are more predisposed to accept that if the camera leaps to Scene A and then back to Scene B and then back to Scene A again, they haven’t missed anything important in the meanwhile, or those actions really are simultaneous. Books can’t be that quick. If Scene A is two characters sword-fighting, and the author leaps away from them for ten paragraphs to describe Scene B where the heroine is confronting the Dark Lord, and then leaps back to Scene A, the sensation is not that of simultaneous intercutting between scenes. It feels more as if the characters in Scene A stopped fighting for a while, then began again when the author returned his attention to them. The effect becomes one of statues.
This doesn’t mean it can’t be done. It means you have to be careful to balance everything, from scene length to tension to the voice you tell the scenes in to how quick the action in each scene is happening.
The best example I know of is Guy Gavriel Kay’s long section in the middle of Lord of Emperors, in which he leaps between a chariot race (being run by a champion with a deep stab wound in his side, no less) and a political intrigue at last blowing up in everybody’s face. He can do this because he uses longer scenes, not sudden paragraphs; because he knows how to use and maintain suspense; and because he’s the master of the omniscient voice where needed. However, it’s good that there’s only one of those in the book, because, good goddamn, I’m always wrung out after reading it.

8) Make transitions between books as like islands as you can.

On one side of the island lies Book 1, a vast ocean of action, description, intrigue, plotting, and so on—the story, in other words, of that book. On the other side lies Book 2, another vast sea. The ideal transition between books is an island. We don’t know what one particular island may look like, but that’s all right, because we know what islands in general look like. The characters are resting on the island, so they aren’t swimming, and it’s solid enough to hold them. More important, there are no charging sharks or pirate ships or moments when the waves are mounting. The characters aren’t left drowning, without a shore in sight.
This doesn’t mean the story need end right after, say, a climactic battle. It’s nice to show the wait or the resting period or the recuperation period beginning. But get the characters to the island before you abandon them, please? Don’t insist that the story end with one character facing a dreadful choice that he must make in the next moment, or a character cornered by rats, or someone falling through the air and possibly going to die, or not, when he hits the bottom. (Remember what I said about leaving characters hanging between life or death? Yeah. It’ll be a real arrow that I shoot you with, I promise).
I’ll answer comments later, as it’s off to class with me now.