Scarleteen

How do I ask my girlfriend about things like our first kiss (we’ve pecked lol) and things maybe deeper than kissing?

I'd say you just communicate about it openly and honestly and frankly like, ideally, you do with anything else.

If this is an area that feels shaky for one or both of you, one way you can do it is to ask if you can have a time to talk about some sexual things you're interested in trying and seeing how she feels -- to have that conversation very much outside an intimate context. If it doesn't feel as precarious as that, then when you are kissing, you can ask if she wants to try a given thing you're interested in and then see what she says (which obviously could be no, yes, yes but not yet, no but maybe later, yes, but this specific way, etc.).

What way of approaching this feels right for you and your specific relationship?

Here's an idea that I find works nicely, especially if it's something that might be new or uncomfortable to discuss. I would either go on a drive or take a walk and discuss it. There's something about the intimacy of being side by side, and moving in the same direction, that is really therapeutic! Plus it allows for the comfort of not staring them in the face the entire time, which can feel very intimidating. I agree with Heather, these conversations are always best outside of intimate/romantic times.
Good luck!!

As long as you don't drop it like a bomb on her it should be fine. Girls like to talk about this stuff too, and we're interested in being open so we know where we stand and where things are going (or not going). Just chat casually about the kisses you've had and ease into the other stuff naturally. Just be honest and not too crude and read how she reacts to it. Her reactions will tell you if you're on the right track or if you should wait till she's more ready.