first time sex

I've been seeing someone for about 7 months now and I think we're going to have sex soon. It's a bit of a weird situation . . . I'm a 35 year old virgin. I'm not saving myself for marriage or anything, it just never happened yet. at this point it's becoming increasingly strange to other people that I haven't had sex yet. I feel fairly comfortable with him and just kind of want to get it over with. I am self conciense of my weight and looks. any tips on how to feel more confident? Or tips in general for first time sex?