Hunter's right.. and I'll this: Your singer is your "frontman"... he or she is really going to make or break your band. Try to get someone with an excess of personality... they may be a bit of prima-donna but its ok if they really bring a great show to your audience. If you get someone who's just an awesome singer though, that may well trump any other concerns.
Hey, don't take it too seriously. Chances are your band won't make it, you'll eventually all go your separate ways, so enjoy it while it lasts, have fun every time you play, and if it goes somewhere, great, but if it doesn't, don't worry about it. I think a lot of young bands try to strategize and put a lot of pressure on themselves to sound a certain way, play certain places, get to a certain "level"... that can all come later. For now, just have fun, and see where it goes. Look at "Foster the People" and "Pumped Up Kicks"... those guys had NO idea that was going to be as huge as it was for them... they were just doing their thing and it caught on.