Drawing and painting manga successfully involves a lot. Firstly, master the fundamentals like line work and composition. Then, build up your color palette knowledge. Also, look at other manga artists' works for inspiration. With consistent effort and passion, you'll improve over time.
Well, to draw and paint manga well, you need to study anatomy and proportions of characters. Also, observe how light and shadow work to add depth. Experiment with different styles to find your own. And don't forget to be patient and keep practicing!