18 and virgin? good to know there are people like you still exist..it's a good thing to not do something in this already spoiled world.. so you must be excited.. here is my 2 cents.. don't talk a lot about it.. disadvantages are i.keep talking about it may seed about it in your mind which would spoil the party, just forget that it's your first time 2.you must be the rider and don't act like a kid to her.. read as much as books as possible and go wild on the night.. be a rider, champ!
My first experience was also with an older girl. Just relax and go with the flow. Don't let it get to your head. Just speak to her and ask her what feels good to her. You'll soon learn that relaxing and enjoying the roller coaster ride with your partner is one of the most satisfying experience a man can have.