When we you start out in anything you have to believe in yourself. I experience this time and time again that believing in yourself and work is key. As a creative person we can doubt our work like no one else can. We tend to fall into the same habits of doing what is easy.
The way that I have gain belief in my work is to trust myself. I trust myself and the process that I go through completion of the work. I had learned that as long as the work is 95% complete in regards to my terms it will be just right. The 95% completion of the work will be as close as it can get to 100%.
I say that because there is nothing out there that is 100% complete. The reason is because there is always something that can be improved or has room for improvement. Being self aware of this is allowed me to develop a stronger belief in my work and myself.
Family, friends, coworkers and whomever do not have to believe in your work. The reason I say that is because its your work! No one has to do anything for you your life is your life. If your clients do not like your work then it could be, a number of things.
With all of this sad believe in yourself even when no one does. If you are not getting clients or making sales of your artwork keep at it. The amount of information out there is endless on you becoming better than you already are. When you start improving and getting better you will learn how much of an impact it can be on you.