Book your travel early.
Obvious? Maybe. But on top of the usual book-early-for-cheaper-flights maxim, there's this to consider: wedding hotels often have a finite capacity. If you're not in the early wave, you might get relegated to the second- or third-tier lodgings -- stuck with the bride's drunk cousins who yell "Yeeeeaaahhhww!!!!" at 2 a.m.