There's nothing wrong with drawing art in the manga style. Drawing bad art in the manga style, though, annoys the crap out of me. Source: am someone who draws in manga style, can't draw for shit, annoys crap out of me.
Focus on getting the basics of anatomy and space first, don't copy "manga", just find how you yourself interpret and stylize reality.
Source: am someone who draws in manga style, can't draw for shit, annoys crap out of me.