Just chill: Uncle Keima will give you some words of advise.
1. Your first time won't be your last time so take it easy. You ain't gonna perform like a seasoned male porn star so chill, anxiety will make things worse.
2. Adopt a 'ladies come first policy' and learn how to please a woman with your fingers, because the first part of you that gets in her pants is your hands, and a guy who knows what he's doing with clit-rubbing (firm circles but not hard pressure) will be more acceptable than a guy trying to shove his fingers up her dry vagina.
3. Ladies like to be touched and caressed, some girls get super hot when you nibble and kiss their necks... for 30 min. (note: For some reason guys get horny, girls get 'hot'. Seriously, I've asked)
4. Learn how to put on a condom on yourself. If you put on a lubed CD inside-out it can slide off at the wrong moment.
5. Sex is messy, always have cleaning products handy. Your girl will thank you when you pass her a towel to soak up your cum from glopping onto her bed-sheets.
6. Talk during sex - ask if shes okay with what your doing. Also tell her if shes wanking you too hard as she might be inexperienced as well.
7. Neatness counts. Unless you look like Bradley Cooper, keep clean shaven as girls really don't like stubble rubbing on them. A well groomed male is always attractive to the ladies, especially those who like cock sucking.