As other's have said, just don't go look for trouble and normally you won't have any, sure there is the chance that you might end up in a bad situation anyway but seriously most of the time it can be avoided.
You should have enough knowledge on how to stay out of trouble by now anyway, I mean for god's sake you're turning 18 soon, you're going to have to look after yourself eventually.
That being said, if you still feel like you can't handle it then schoolies isn't for you and in that case just don't go =_=. Chances are you won't enjoy that kind of partying anyway.
I believe this so called "schoolies" if a preposterous idea.
I for one am not impressed from the lack of maturity that those former students show.
It's just another event where future rapists, wife-beaters and criminals have the excuse to show ludicrous behavior.
If you're implying that schoolies shouldn't even be held because of this very small minority of people, then you're an idiot. Those kind of people will be around anyway, why should their foul existence be a reason that others can't have fun. As I said before they are a minority anyway =_=.