I'm having a girl come over in a few days and I've never gone further than kissing a girl and I've never had my dick touched by anyone apart from myself.
I'm 18 and my foreskin is very tight and I can't pull it back properly when erect, how do I loosen it?
Cut it, snip snip
Put on a condom without pulling your foreskin back. If you have picked the right size condom you will be fine.
You do not need to loosen or retract the foreskin for sex. Leave things as they are; just make sure that you're clean and smegma-free before she begins playing with you, because girls like their toys clean.
Also, >>18524358 is right: don't forget a condom.
>>18524358
It feels a Lot better with your skin retracted. Fucking with foreskin up is like wearing a skin condom. I'm uncircumcised but never had problems retracting. You should have been retracting while growing up, man. Did no one tell you? You can work it out, just takes time and effort to loosen it up. People turn their ears into giant, gaping holes for literally no reason, you can get the turtle out of his shell, mate. No worries. It's probably gonna hurt though. Google for guides..