To be honest, i think that no amount of 'how to draw these characters like this' will help you become a better artist in general. Focus on getting the basics of drawing in general down without going for a preset style, lik " the marvel way". If simply doodling is not your idea of drawing and practicing, you can try to use a character that already exists like naruto for example. Maybe start out by taking his body without the characteristics of naruto.
Try to design your own clothes around the shapes of his body without referencing the manga of naruto.
Try to use the body proportions to design a brand new character. Instead of drawing someone with an athletic body. Doodle a fat guy in naruto outfit.
Another fun thing i like to do is to randomly draw some lines/ swirls on paper and try to create an actual character by. Using and adding extra lines.
If you feel comfortable with that, design your own body proportions and build your character.
The main advice i can give you is:
Draw what you want. Dont accept any less than the image in your head.