So many artists worry that their work isn't good enough and it sometimes keeps them from painting at all. Are you doing your work for yourself or others? Whatever the case you should do it like nobody will ever see it but you. Do what you're passionate about and others will see that passion. Not everybody will like it but you will eventually find an audience. Don't find a trend and ride it. Be yourself and be original. Nobody but you can paint like you can. I know so many artist that don't do anything just because they can't please everybody. What others see as good art may not be the case. No matter how famous or good an artist is there is going to be somebody that wont like their work. That's true with everything so don't try so hard to please everybody. PLEASE YOURSELF. There will be some that will like your work and some that wont.
I know art is a personal thing and it really stings when anybody says something negative about it. One thing that has helped me is "a reaction is better than no reaction even if it's negative". One of my favorite reactions I ever got from somebody about it was very negative. They said my work looked like "luminescent vomit". It was a negative comment but a passionate one. They couldn't even stand in front of my work for more than a few moments. They said it was too disturbing for them.
You should get to the point that you will quit taking commissions that you don't want to do. I used to take any commission. I got to the point I didn't even want to work on the personal things I enjoyed because it was taking time away from my deadlines that I didn't want to do. If you're into painting dragons or mythological creatures don't do sailboats or barns unless you just desperately need the money because it will leave a bad taste in your mouth and a lot of times look dead to others because you hated doing it.
Picasso said "Every child is an artist. The problem is how to remain an artist once he grows up". Do you remember when you were young sitting at the kitchen table drawing with your crayons just to be drawing? Then the older you got people told you what was good and what wasn't and you accepted it. You only enjoyed it when others gave it their approval at that point. We were born artist and society convinced us we wasn't.
Art is a very personal experience and no one should be able to dictate what you should or should not paint. Paint like you are the last person on earth.
JUST DO IT!!!