Writing a manga may sound easy for something that is read with pictures well it's not. Writing a mnaga is pretty challenging you want your own a original story that doesn't sound lame. You want to write down any ideas that come into your because those ideas can be what your manga is about. Also choose what kind of genre you want your manga to be for example theres romance, shounen, comedy, etc.

When you get ideas write about the ones you feel very motivated to do write the one that makes you feel proud that your writing a manga. Write about the one that makes you feel proud that your writing a manga. Also when your writing the story make sure it's original. You want to sound original because more people will be attracted to your manga and think it's awesome or needs working on.

Whenever your creating a character there are many different ways to make one. You could use blood types to make a character. Many manga characters are created from using these blood types.
O- creative, optimistic, strong-willed, self-centered, and unpredictable
A- creative, reserved and responsible, but also stubborn and tense
B- active and passionate also selfish and irresponsible
AB- adaptable and rational, also forgetful and critical