AstroGlide is a good thing. Even more so when used with a lubricated condom. Speaking of which, a friend of mine accidentally bought UNlubed condoms one time and she told me it felt like her uterus fell out. So always check the package to make sure it says LUBRICATED.
I prefer Durex brand condoms, personally. Especially the "Natural Feeling" style.
Don't plan on having sex for hours the first time. Since you're a virgin it won't last very long. I've never been with a virgin, but I've been with women who might as well have been. It never lasts long when a woman is that tight.
Don't expect to come or orgasm your first time. Not unless you've already had one. But even then you'll be in a good amount of pain and might not be able to.
If you don't already, I would recommend both of you shaving "down stairs." Pardon the phrasing, but it makes for a smoother ride.
As far as "prep" goes, make sure that you yourself are adequately wet before he goes inside of you.
Anything else and I think I'd be repeating silvertae.
Best of luck.
OG