I normally do basic 3D models, and I'm very unfamiliar with pixel art.

Any tips?

Are you planning to make a 2D Game? I found Aesprite to be quite good (although not free).

I’ve also had students who liked Lospec: https://lospec.com/pixel-editor/ And Piskel: https://www.piskelapp.com/

I’m not an artist but I’ve noodled my way through a couple things.

It might also be easier to start with some templates from https://opengameart.org/ and modify / add to them rather than starting from scratch.

I hope that helps :D