- Some readers do skip prologues -- they can't wait to start on a story, and they see "prologues" as something before/outside of the main story, something not necessary for the story. They go directly to something marked "Chapter 1." As writers, we have no way of dictating how these readers read, nor should we condemn our readers if they ever skip prologues -- they've paid their $10. So if you have pertinent and important information and you only present it in the prologue, you may risk confusing some readers: "Huh, where was this ever mentioned?" It doesn't mean you have to change your artistic vision because of these readers, but do keep that in mind.
- The first page is very important, whether it's chapter 1 or prologue or whatever. Treat your prologue, if you have one, as carefully as you treat your first chapter. If you don't hook your readers right off the bet, you risk losing them. You can't say "oh, it's just a prologue. The real meat begins in Chapter 1 anyway..." That includes info-dump, long descriptions of settings, "ordinary day" where nothing of consequence happens, navel gazing, etc. If you won't put that stuff in Chapter 1, you shouldn't put it in a prologue either.
- When so many writers misuse prologues, don't be part of the trend. Make sure there's a clear purpose for the prologue, and that it's the best way to tell your story.
- A prologue doesn't need an epilogue, or vice versa (Atonement, for example, has an potent epilogue but no prologue). They often go hand-in-hand but not necessarily so. Also, a "frame" is a specific prologue-epilogue pair and it serves a key role in some storytelling and can be very powerful way to structure your novel.