If you feel like have enough technical skill to do some commissions of people's characters, but have no idea how to make art "presentable." The main focus of a drawing is always the character.
here are some tips that will be helpful:
Better no background than a shitty background.
All of your backgrounds, when you use them, look very messy and noisy. They detract from your subject because of that. They obscure the shape making it harder to read, and attract attention due to noisiness, harsh diagonal lines or contrast.Give more space to your subjects. Adding more space around your drawings will help pull focus to the subject itself, s well as avoid any weird 'boxed in' feeling.
Make sure that overal values are balanced, making your drawings not look dull and uninteresting.
Have a simple, low contrast signature, and put it as much as possible in the same place, not too close to your drawing. You're ruining your pictures with those nasty black blotches.