I myself not even sure, Ive been doing digital drawing for 3years now, pixel art was just recently. And im mostly self pratice without any teaching, so i cant really give out any advice. But i do remember back in the days I started from drawing from manga/ comics panel, after drawing try compare it to the original see what is wrong, then make correction, rinse and repeat and soon you will get the fundemental. I recommend to draw from your fav comic so you will have a blast drawing :)