I do not know how many times I have seen teenagers, as depicted in novels, to be so easily fooled and all for giving up their virginity. I mean, how often have you seen a teenager fall madly in love with the tall dark stranger at the back of the room? Multiple times I bet.
If you want to include a teenager in your novel, and you happen to be one, try not to let your wishes and fantasies get the hold of you. Teenagers are often lazy, tired and usually self-conscious - but don't let yourself think there aren't those certain ones who are wonderful students, who excercise daily but who are secretly the avid party-goer. See, what you have to remember is that not one teenager is the same- not every teenager you meet will be timid, or the beautiful girl who thinks she's ugly - and if you write like that, your reader will certainly grow annoyed.
You have to be careful while writing a teenager in your work - they are tricky, often changeable creatures.