How do I prepare for sex?

So I’m 18, never had sex other than once but it wouldn’t go in & it hurt so he stopped. The first guy was smaller than this guy so I’m just worried this is gonna be another embarrassment and I WANT to do it but it just hurts. Even getting fingered hurt, feels like a bunch of pressure down there. I’m not trying to rush it either, but it’s just gonna be the same dilemma with every guy i decide to have sex with.

When I masturbate I only do clitoral simulation and never penetrated before