i'll say it ~ anyone who has questions about prologues shouldn't write them.
harsh? maybe. but, i've seen enough prologues that simply have no excuse to exist. it'd be *something* were they as interesting as the writer thinks they are; however and alas, the reader really doesn't need to know how the universe was created. again. and by 'light' and 'dark' being no less. okay, granted, this 'creation prologue' nonsense is what you find in fantasy (at least the stuff i (did) critique back when i had a spare second) and may not be applicable across the board.
the simplest question to ask and the hardest to answer honestly is, 'what's the purpose of the prologue?' by virtue of it tumbling out of our heads we deem it good. and i wish i had a nickel for every time someone said, 'but the prologue is crucial!' when in reality it's probably not. if it's backstory, it can typically be weeded out as any other bit of backstory (i'd venture to say that the most popular method is through dialogue (the slight variation/cliche here being a storyteller recounting the battle of such-and-suck around the campfire), but be mindful of not doing the 'well, bob, as you know...' thing).
taking it a step further, once you get your non-prologue version set to write you'll probably come along the advice 'start off with action.' this, too, i think is bad advice. in lieu of some stupid bloodletting opening (being chased by dark riders on the way to castle ravenscroft or some such lame, tired crap), a slower opening forces the writer to create *pause for dramatic gasp* compelling characters. (imo, it's a more mature approach to writing. unfortunately, fantasy writers aren't reknowned for their high levels of maturity, a lot of 'em being kids who are still in that 'death' phase.)
so, using an interesting prologue and then starting off with the real MC in the midst of their daily routine is a bad thing? i'm screwed then. when i actually do a prologue, it's usually a world-building deal and showing an example of what life is like... as long as it rocks. if ever you see me write how the gawds created the galaxies, then cut to a young, poor, female thief jumping from rooftop to rooftop, just to wind up in a tavern where the thieves' guild hangs out, you have my permission to murder me. stop me before i kill more pixels. after all, the slaughter must end with more slaughter, no?
where was i? oh, yeah, stay out of my booze.