Exposition, especially in genre, can be the real killer.  Exposition means explanatory writing, like an essay or newspaper article.  You've done a lot of research or drafted a new world from scratch.  You want to share it with the reader.  Also, in order for the resolution of the work to make sense, the reader needs to know all kinds of things about the characters' back stories and the world they live in, the vital cultural or mythic details that the climax may hinge on.

As the author, you need to find ways to deliver all of this information.  Before you just drop in a few paragraphs (or even one) where you explain anything to the reader, ask if there is a better way.

First of all, your reader may not need that much in order to enjoy the world and the story you are about to tell.  The plight of a nation is only compelling when you care about a character involved in the fight—so just writing a few paragraphs of history is unlikely to engage the reader, whereas showing the princess running through her ancestral home, grabbing the two treasures she can carry before escaping gives the reader a reason to wonder.  Snip the history into little nibbles you can disperse when the reader really wants to know.  And make those two treasures not only extraordinary, but culturally significant—your description can serve double-duty.

It's much more fun to discover a place by moving through it with the character.  Give enough setting to let the reader get a picture of the place.

Instead of telling lots of things about the place, create scenes that will give you the opportunity to show what the place is like and how people are there.  You might think of it as a mystery: certain clues need to be planted.

You also need some number of red herrings, in this case, the cool stuff about the world or the character that won't actually develop into plot points.  If you need the reader to know that white is the color of death in this nation, give a glimpse of a funeral or graveyard.

Back story is a particular kind of exposition that is often given too much attention.  It should be informing your character's actions, not overshadowing them.  Again, the reader doesn't need to know a lot about someone she's just met: she needs to get to know the character, to become engaged in the character's goals and problems, before the back story is entertaining.  When I say that the back story "informs" the actions, I mean that it influences behavior, manner of speech and appearance, and relationships, even if you haven't specified what the back story is.

For instance, if you want the reader to know that your character used to be royalty, but is now in hiding, you might give her clothes that are too nice for her surroundings, let her dialog be regal, her manners impeccable—to the point where the peasants around her think she's putting on airs.

In particular, pay attention to the emotional context of back story.  The child abandoned by his parents at an early age will have different responses to family dynamics than the one raised in a happy household. You could spend maudlin paragraphs describing an unhappy childhood, or you could show a brief interaction where the character seethes with envy when selling a toy to a cheerful mother and grateful child.

When you consider shifting the pace of your work, especially a novel, examine the weighting of scenes.  That means the amount of attention given to any particular moment, either by you the author, or by the character experiencing that moment.

Look at how many pages the scene takes versus what actually happens in the scene.  How much progress is made in the plot?  What character details are discovered?  How important is the conversation that takes place?

It is often the fault of the novelist that we get wrapped up in something that is fun (or difficult) to write, or we enjoy certain types of scenes or think them necessary to the story—and we end up inflating a minor event such that it takes on great importance in the mind of the reader.  Later on, the reader feels disgruntled because they spent all this time with something that was only slightly relevant.

For fantasy writers, this often means setting or cultural detail.  We lavish our love on research and world-building, then give the reader a grand tour of the city—a city that turns out to be merely a place where the characters spend the night, never to return.  If you have a setting with high coolness value, make it work in the book: set your important moments there, or even discover things about the setting that can lend significance to the story you want to tell.

Worse than the extended scenes that don't advance the plot are abbreviated ones that do.  Too often, important moments that have been built up to or that contain compelling emotional resonance are given short shift, handled in summary, off the page, or whisked away in witty dialog. Indulge the richness of your language, your enthusiasm for character and setting by enhancing the scenes that really matter: big turning points, climactic meetings, moments of revelation when the character has to absorb a life-changing event.

What are the most exciting, most heartfelt, most catastrophic moments in your book?  How many pages are they given?  How clearly is their impact felt through the protagonist?  It's possible to create a short scene (less author attention) but give it weight through the impact on the character, and its on-going importance to that character.

If you have emotional resonances or relationships that will grow with time, you may not want the first mention to be very long, calling too much attention to itself, but you want it to feel important.  Ground it firmly in your character's point of view.  Look for an image or phrase that you might refer back to later, when you want the reader to recall this small, but significant moment.

One special tool in the novelist's toolbox is the chapter break.  How you open and close chapters creates the rhythm of the work and has a great effect on the reader.  All too often, beginning writers start with a character waking up, and finish with the character going to sleep or otherwise reaching a state of rest.  I can feel myself yawning already.

Every once in a while, you need that mundanity, usually to counterpoint a time of high conflict and action, after which everyone needs a breather. One chapter in my latest novel opens with the protagonist waking up, well-rested and refreshed—then realizing that this means the sick child she's tending has not coughed all night . . . so the waking quickly shifts from idyllic to ominous.

A general approach to scenes is to enter as late as possible to when the critical events take place and leave as early as possible after that.  Allow the impact to develop upon the reader rather than try to explain it with dénouement (the settling that occurs after a climax).

The same can be said of chapters.  Many authors have a great instinct for the type of close that makes the reader want more: a new question is asked, a secret is revealed, a key action is faced, a life or future hangs in the balance.  But instead of bringing the reader to that wonderful moment of tension then breaking the chapter on a gasp, they include another paragraph or two, a few more lines of dialog that release the tension early, or extend it by obscuring the impact of the moment.

A chapter break can be clean and firm: a snap.  Or it could be more gentle: a sigh.  (please, never a snore).  Different kinds of chapters (and different kinds of books) call for one type or the other, but it's nice to include both the stunning cliffhanger and the pause for reflection.  Even a driving adventure plot can use a romantic scene or humorous interaction.  If you're doing your job, the reader will enjoy this little break, and spend a little quiet time with the characters while wondering what upheaval will start the journey again.

For those reflective moments, it's nice to close on an image—either symbolic, rich with sensory information, or indicative of the character's mood.  Instead of telling the reader what the character is thinking, allow the reader to absorb the character's stillness and interpret from what is left unsaid.  Evoke emotion rather than force it.  Then grab the reader with the start of the next chapter as they scramble to keep up with your character's next adventure.