You just learn better when its your favorite character. Fun is such an important part in learning to draw and it's not often talked about. The facts are rooted in learning science.
So don't talk yourself out of drawing the fun stuff. You don't have to suffer to learn to draw.
Pick your favorite character to practice art on. Then choose ONE fundamental at a time to study until you learned it well before doing another. I get that beginners want to study everything at once, especially seeing everything on a book.
But I tell you, pick only one at a time.