You want to be a professional artist. Where do you start? First of all there is a major difference between making art for fun, and making a living by selling art. Your work needs to be good. I don't mean kind of good, I mean good. You need to hone your craft. If you make art out of trash cans, then by gosh make the best, most interesting, technically well made trash can art around. Next, you need good photos. Semi good photos will not work. They need to be flawless. A good piece of art can look bad in a bad photo, and a bad piece of art can look good if shot right. If you are a bad photographer, have a friend shoot your work, or pay someone!
Make bodies of work. You can't have one work that looks like it is one genre and another from a different one. No! This doesn't work. There needs to be consistency of thought process. Also, when you keep going with one thought it gives you practice, and practice makes perfect.
Create your own style. Can people look at your work and know that it is yours? They need to. If they don't, you will not get anywhere. Copying other people's style is a bad move. Create your own voice.
I'll do a post soon on how to photograph your work at home.