I am in no means an expert when it comes to art but I tend to be good at offering advice. From my experiences an artist's worst enemy is themselves. More than half the battle is agreeing on what's good. A way around that is to drown out the negative and focus on the areas that you feel you are good at. So long as you're proud of your work then what others say won't matter. From an artistic point of view my old art teacher told me that the key to great art is mastering shading. Shading adds depth and volume to a piece and if you can get it down properly the results will speak for themselves. I hope that helps out