Here are a few tips:
Do not allow yourself to become isolated with a guy you do not know or trust.
If you are at a party, stick close to your friends, and look out for each other.
Drugs and alcohol are factors that make rape and sexual mistakes much more common, so stay clear of these. If you are of age to drink, know your limit and do not leave your drink unattended. Do not accept an open drink from another. The reason for this is because date rape drugs are easily dissolvable, and are commonly slipped into the drinks of unsuspecting women. Better yet, don't hang out where anyone is drunk.
If you're on a date with a guy, be straightforward about your boundaries and keep it pure. Of course, a gentleman should always respect your "No" or "Stop" no matter what, but too much intimacy creates sexual momentum, and even a guy who intends to respect your wishes might not always stop when you want him to. I do not say this to excuse a guy's behavior or to place blame upon the victim of his abuse, but to alert girls to a potentially dangerous situation. One study of date rapists found that every instance of sexual coercion followed other sexual behaviors that were mutually agreed upon. The rapists simply refused to heed the woman's refusal to go further.[1] So, out of respect for him as well as for yourself, save the passion for marriage.
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[1]. E.J. Kanin, "Date-rapists: differential sexual socialization and relative depravation," Archives of Sexual Behavior 14 (1985), 219-231.