Eh, how to draw manga books aren't exactly the most helpful hings. Sure it gives you a pretty good sense on how to start, but it really just teach you the most basic of things in manga drawing. I mean, most of the time I view real life people and see how the body looks and works before attempting to adopt it into a manga style.
In the end, how I basically learned how to draw better came from a series of online tutorials, auto-deduction and a whole lot of practice.
Aaannnddd despite my better-than-average art, I've never actually drawn fanart of any manga/anime series. Yeah. I don't like to butcher characters with my shitty art hahaha.