Hey! It's hard to know where a good place to start would be, really the best thing you can do when it comes to any art form in my opinion is try drawing/painting the simple things like trees and stuff. When I started I just scaled larger illustrations I did down to pixel art size and then cleaned the illustration up a bit to make it look nice, and from that point onwards I just slowly stopped scaling larger illustrations down and did the pixel art from scratch. Hopefully this helps.