Seeing as an Artist
What is it that makes a painting stand out from the crowd. I believe it is the underlying structure (big shapes) that make a painting successful. The details and refinements that we are tempted to add at the end will not correct a badly designed or poorly structured painting. We can think of it also as the bones of our painting! We can always add but we cannot take away!
It is important to learn to see and draw as an Artist. That is learn to see the big value shapes and design our painting with these in mind. If the underlying structure is good, then our painting has a better chance of success.
All the fanciwork in the world cannot help a badly designed painting.
To improve your design, study books on the subject of composition and design. Continually practice your drawing and make small value studies before you commence your painting!