spring rush

Get to know someone in a house you're interested in. Try to befriend them, contrary to popular belief most guys in fraternities aren't complete ass holes, so just try to hang out with them. Smoke them out or play some sports or something just get to know them on a more personal level. This will help you out tremendously. During rush brothers meet tons of kids, most of these kids will just say their name, shake your hand, ask a couple questions and then go away and repeat this on another brother. DO NOT DO THAT. You will not get a bid anywhere by doing that. You need to have genuine conversations with people and make them remember you, but in a good way. It's quality over quantity, you could shake every brothers hand and have a 2 minute conversation with each one and you'd be MUCH less likely to get a bid than a kid who meets 10 brothers but has a 10 minute conversation with each one.
Also, try to join one where you'll fit in, if you don't know anyone and don't really have the same personality as guys in a house the chances of you getting a bid there are much much slimmer. Plus it's for your benefit to be surrounded by people who act like you, you'll have a much more fun time, I know plenty of guys who feel like they could've been happier in a different house, but chose their house instead for the reputation it carried with it.
Don't just join to party either, and certainly don't tell us thats why you want to join. You're almost guaranteed to not get a bid if you tell us that