HOW do i suck dick

When my boyfriend and I first got together, I gave good head...but once we started having sex I went a while without giving oral and now whenever I try, I feel like I'm doing it all wrong. It's like I forgot what to do and I can still make him cum from head, but I don't feel as good about it anymore...

I also used to be able to let him throat fuck me and I can't do it without gagging anymore!/:

He hasn't complained or commented on it or anything, but my insecurity about giving head has left me hating it.

Advice. Tips. Help me.