I would hope that prom could be an experience that sets a precedent or a habit, in the sense of how you approach parties for the rest of your life.
If you decide that the point of parties is to get laid, you will have a bad time at parties. This is a fact. If your only expectation is to get laid, you'll have a bad time and you make the experience worse for everyone else. Even if the expectation is reasonable you should still detach yourself from it.
To give an example, I was at a 'marriage' party. At these parties individuals marry each other just for the night. It's kind of a silly joke thing, but it's exactly the type of theme where people expect to get laid. You bring a date to 'marry,' you might even marry a random stranger, you might marry your most innocent, platonic friend. You might walk up to that hot chick and ask her if she'll marry you. It's not an innocent situation, you have to respect this as the opinion of someone who has experienced it: this party's theme was very sexual, and many people were hooking up.
Anyway, my friends and I were sitting around drinking in front of a fire pit, and there's a dude who walks up and starts bitching about how his date ditched him and how he wasn't going to get laid when according to him 'everyone else is going home with company.' He was moaning about what a terrible experience he was having, and on and on and on.
The group I was sitting with was having a great time, and none of us were going to get laid that night. Some of us had dates, some of us married random chicks and then ditched them, some of us just chilled the whole time. And now we were sitting and talking and shit. This guy really didn't understand that our different expectation for the party was what allowed us to enjoy it. Getting laid would have been great, but we were all much more interested in enjoying meeting people and drinking and dancing for the sake of fun.
You don't want to go into any social interaction with a big expectation, and I think that frequently the sexual expectation leads to poorer experiences. This concluded my first point/
My second point concerns sex:
Everything that anyone tells you about sex is simultaneously true and false. Sex is shrouded in such quantities of mystique and glamour that I would consider only what I personally have experienced, sexually, as a fact about sex. It's a very diverse activity.
If you have sex for the first time on prom night, or any night, it will be terrifying, weird, and likely horrifying when you look back on it. Don't expect to have good sex or bad sex (there is no need for you to have bad sex on your first time, it just tends to be that way). You'll probably be relieved when it's over.
Lastly, when you start partying in college, drink all the booze. This may sound like bad advice, but I promise it isn't. pinky promise, cross-my-heart-and-hope-to-die, this is sound advice.