Well, to draw manga well, you should focus on character design. Make your characters unique and expressive. And pay attention to details like hairstyles and clothing. Another important thing is to master different line weights for a more dynamic look.
Drawing manga requires a lot of practice and observation. Look at other manga works for inspiration. Work on your shading and highlighting techniques to give your drawings a three-dimensional feel. Also, don't forget to plan out your story and panels for a coherent narrative.
You need to start with basic shapes and proportions. Practice sketching simple figures and objects first. Also, study anatomy and perspective to add depth and realism.