Little Paintings

So I am trying to think of what paintings i can do that are 18x24 or smaller so i can enter them into the quality section but I'm not quite sure what to do. I have never worked that small before so i have no idea what they will look like. Should i do some stencil things like i did with the tree one? Or, stick to the more graphic and layered concept i did later on with my stuff? They need to be good enough for quality so any suggestions?