I don't think you'll find a specific tutorial for this. Basically, you just have to combine knowledge from hand-painted textures with pixel art. Your best bet is to look for tutorials for making hand-painted textures, and then look for tutorials on pixel art. For hand-painted textures, I suggest you simply go through the…
Well helo thar friend :D I'd say the textures' levels need a little tweaking, and if I was doing it, i'd probably go in and do some pixel-by-pixel "clean up" of some of the textures, particularly cobble stones and stuff like that. Doing pixel art crap on this kind of texture can be a bit fiddly but the end result will look…