Scared to have sex in college.

So Im a first year 19M. I generally no problem getting a girl and always get to the point of making out. However I have never progressed to sex. I have had sex before but when it comes to college parties and clubbing, I'm afraid with drinking involved that it will lead to the girl saying it was non-consensual. Despite If I asked for sex and she said yes, Im still afraid she would say it would be non-consensual. Can someone explain how to truly do a casual hookup, safely with both people giving consent?

Any help is much appreciated

Thanks