Lots of things to consider. The emotional impact, The future, Your Relationship and of course, STDS.
Emotional Impact
As far as I know, sex has a great impact on relationships and the emotions of both partners, especially the girl. Some people say that a girl will become a little more insecure after losing her virginity to a guy. I believe this is mainly because she's given up her virginity, something you only have once in a lifetime. So after giving yourself to someone, usually the girl will want to make sure that the guy won't leave her right after he's gotten "what he wants". It's not true that guys only want girls for sex, but because many do, some girls will get the general idea in their head that after the guy takes her virginity, he won't need her anymore.
I don't know this for sure, it's simply based on knowledge and experience, but it's probably something to consider.
How will sex effect the girl's emotions. If it makes her a little more insecure or clingy, will you be able to handle it?
And if she falls in love with your cock, and wants it more often, can you handle that? Lol, that part's a joke.
The Future
Use a condom. If not, make sure you're ready for what may come. A child is something that requires countless amounts of time, emotional support and money. If you can't handle it, don't do it.
Wrap it before you tap it.
The Relationship
Eh, I've always felt awkward after sex with a girl, though.. in some cases we never spoke of it again. With situations like those, where you never see the girl again.. it's no big deal. Not to me anyway. However since this girl wants to do it with you for sure, consider how the relationship will be after sex.
If you think sex will ruin it, maybe you should wait. But if you think all will be fine, go on ahead. I recommend discussing things with her though. See how she feels about it, if you want.
STDS
Assuming she truly is a virgin, this probably shouldn't be much of an issue. However, I'd recommend being sure of it. You don't wanna have sex with someone and regret it later. I have too many peers (and quite a few family members) who have done this in the past.
There's more, but I'll stop there.
Also, post pics of it when you're done.