He is the person to ask!
They don't often show it on TV or the movies in sex scenes, but in real life, when people have consensual and satisfying sex together, people talk to each other and ask each other questions.
So, assuming you also WANT to touch your boyfriend back (if you don't, or don't feel comfortable yet doing that, you get to decline), you do this: you can say what you have said here, and have a talk together where he can tell or show you, himself, with his own hands, what he likes.
Or -- or additionally -- you talk as you go, asking him what he'd like, trying that, then asking as you go if what you're doing feels good or not.
And by all means, if we're going to be touching people's genitals, for general safety, we don't want to do it with anything that could cut or hurt them, so you can cut or at least file your nails, or put a latex glove on if you're full-on dragon lady and don't want to change that.
But no one BUT your boyfriend can tel you what he wants, what he likes, what feels good and what doesn't, what's pleasurable and what's painful. Lucky for you, he's right there to ask!
