Since I did not teach my usual expository workshop at SCWC in Irvine last month (the conference was great, by the way!), I thought I'd do a little recap rant, um, lecture about the subject here.
First, what is expository? Expository is everything that happened to your characters before page 1 of your novel, and everything that happens between the book's chapters (or "offstage") during the course of the book.
Nothing makes me quite so crazy as expository dialogue that simply states a bunch of facts about the character or situation; the spoken lines may be within quotes, but it is not written in a way that any human being would actually speak to a friend, spouse, or family member.
Often these clunky lines begin with "Remember when we...?" and unless the person who's being addressed has dementia, they probably do remember when that happened, or the character who is asking wouldn't be asking.
This sort of "info-dump" is often found early in a novel and is the reason that I could eliminate—sight unseen—every first chapter of every first draft on the planet with no loss to modern literature.
To make this sort of thing work, you need to either keep the dialogue incredibly brief, or have your characters speak in "code" such as having a wealthy person say to their spouse "It's time to bang on the radiator" in reference to their early poorer days, instead of "turn up the heat, won't you, dear?" Do NOT get overly detailed and tedious by stating how they used to bang on the radiator to get heat back on East Fourth Street walk-up apartment they shared way back when.
If this memory is crucial to the plot or set up, have it happen in the character's thoughts, or at least have them recall it out loud to a stranger, not someone who was there, experiencing it.
Dialogue isn't the only offender when it comes to expository, of course. Writers have so much information stored up in their heads about their main characters that starting on page one they want to share (dump) it all with us right away. When this is included sparingly in thoughts or in descriptive prose, it can be very effective, but all too often it makes the novel feel old-fashioned and amateurish.
Remember that we only need enough info in Chapter One to read Chapter Two and so forth. The reader doesn't need—or want—to know everything about the book's protagonist or their present life situation right away; we want to "get to know them" just like we do with a new person we've met. Someone who tells you their life story in the first encounter is often viewed as a narcissist, or just a bore.
Portion out info slowly, like you were rationing hard to find staples during war time...don't use up all the butter on day one of the month. Make us wonder, keep us curious. We keep turning pages, after all, because of what we DON'T know, not what we know.
Authors should always self-edit their first (or fifteenth) draft as much as they can prior to sending it to their friends or Beta readers. Try to get as many eyes on the manuscript as possible before you start spending on an editor.
Not only will it save you money and time, but we editors can do a much better job if we are not hired to simply improve something that is clearly flawed, but rather asked to make something good into something great.
This should be obvious, but getting more eyes on a project is especially important when one is self-publishing.