As a digital artist you clearly have quite a lot of technical skill (in terms of working with layers, manipulating images, neatly over-laying etc..).
The above are good, however they are missing certain professionalism.
My advise would be to observe more... if you plan to spend 3 hours working on a project, spend at least an hour looking at similar work. Familiarize yourself with artistic rules: complementary colours, the rule of thirds, the golden ratio etc. Then try applying these principles to work you find (you will be amazed how rigidly even the most original of designers follow them).
Keep it up!