preparing for first time (tips and advice please)

So I decided a while ago I was ready to have sex for the first time with my boyfriend of 7 months. A couple weeks ago we tried and he couldn’t keep it up and it was just hard to get in. I’m super comfortable with him and I trust him but I’m just scared he’s going to want me to do advanced stuff I have no idea about. I just don’t want to embarrass myself and it not work for a second time. I’m not saying I feel uncomfortable like we talked about it and he’s really understanding but I just want it to go reasonably smooth. Soo here are some questions I have for my more experienced girls.

What position should I do for my first time?

What helps it go in easier?

Just any tips in general xx