TheKrisPandemic saidBy losing your virginity do you mean taking it up the ass?
If so, take a shower together and make sure you're both squeaky clean. Do a lot of foreplay before hand, and I've heard rimming helps loosen it up pretty well. But again, make sure you're both really clean.
Lots and lots and lots of foreplay. When it's finally that time, make sure he goes slow and DON'T GET STRESSED!
That's my best advice for you. Hopefully an actual bottom will come in here and give their advice since they'd know a lot more than me. ;D
Actually, that is generally the advice one would give.
Practice on yourself, even if it's just a finger or two if you're going to bottom. Get used to the feeling and what not. The more it feels natural-ish to you, the better you'll have it when it comes down to the moment.
And that post with alcohol? It can actually help loosen up and easing your mind.
Like he said... take your time... after a while there won't be any pressure and you'll just be able to go at it.