Dirty talk

So my boyfriend and I have a great sex life, the only thing I have trouble with is he has asked me a few times to talk dirty to him. I've tried every time but it was a bit awkward for me because I really had no clue what to say then I'm trying to think and it ruins the moment for me because I'm stuck thinking 'is that too dirty?' or 'is that sexy enough?' 🙈
I've only had sex with one other person which was my first and there really was no experimentation or talking or anything of that sort so this is very new to me and I was wondering if anyone here has any pointers on how to go about this 🙂