I don't think there's much of anything that Greeks as a whole look down upon, with a few big exceptions (murder, for example, or being out and out racist). But each chapter will have different ideas of what they want in a girl. Chapter A may say, "She dresses too slutty," and B will say, "Oh! She's so cute!" Or C likes girls who party, and D doesn't.

So assuming your wild stuff is (mostly) on this side of the law, excluding a little partying, you should be fine! If you're outgoing, you'll just naturally find the chapters that suit your personality.

Tara,
Basically, you need to just be yourself! If a particular sorority doesn't like you for who you are, then why would you want to be their sister? Just be cautious not to bring up particular topics during rush such as guys/boyfriends, partying, etc. Trust me when I say that the sisters won't bring up those topics either. They are big rush topic no-no's. If you have a questionable reputation there is a chance they will find out about it anyhow, unless you are going far away where no one there knows you. Like everyone else said, most sororities and/or Greek systems are diverse, and sorority ABC may have some very outgoing girls, some shy girls, and some in-between. Some of the most important things sororities look for in a potential new member are:

-high GPA
-friendly, caring personality
-enthusiasm & spirit
-involvement in extracuriccular activities

You will be pledging a sorority, not joining the CIA, FBI, or Foreign Legion. Everyone has done something crazy in their life.

Just be patient. Focus on your high school graduation. :):)

Good Luck:) :)