how to relax

during sex? i'm no where near shy any time unless it's during sex or anything relating to it. i'm so caught up in my head thinking about what to do and what not to do. my biggest issue is initiating, guys like girls to make the first move sometimes but i am so nervous i just can't get out of my head. the only time i'm not nervous or shy or anything is when i've had alcohol. i lost my virginity late (19) and i've only been with 5 people, one of them was more than once though the rest were one time things. :( help