Just be yourself, tell him how you feel and if he is a good guy he will make sure you will feel comfortable.
Let him know if he is being to rough, going too fast etc, you want it to be a memorable and enjoyable experience.
Enjoy and bring your own condoms!
lube may be necessary
she should tell him to go slow (idk i guess depending on his crayon size) & to ease in, pull back, ease in a little bit more.
relax, even if it feels dumb & requires heavy breathing.
don't try to do things you know good & well you don't have the experience to pull off (my bff told me to this v interesting sex trick & i was like wtf????)