For art to impress, it’s helpful if it readily catches the viewer’s eye.
If you have your work scanned in on the computer, looking at the file thumbnails is an excellent way of quickly seeing what an art viewer sees as they pass by.
A similar effect can be had by putting the painting or drawing across the room from you and glancing at it quickly. This is how you can truly tell if your work has good contrast and interesting composition.
What pops out at you? What is the first thing that you see? Is that the main focal point of your work, or can you think of ways to make the art more impactful?