Here is an interesting exercise you can try: paint a series of non-objective abstract studies on a single sheet of paper, all at the same time. I discovered this by accident. I was commissioned to do a watercolor landscape of no place in particular and I didn't know quite where to start. So I took a full sheet of 140# Fabriano cold press paper and divided it up into squares. I used 1/2 white tape to make clean a clean edge between images.
Then, without planning anything or having a pre-conceived idea of what I wanted, I started laying down color. I painted large areas of solid color, small shapes, wet paint on dry paper, colors mixing on wet paper, gradated washes, everything. I painted all of the squares, one after the other, all at once, without stopping to evaluate or ponder. I was bold with color, and bold with mixing unusual and illogical colors. I was free to paint like a child who doesn't know all the rules he isn't supposed to break.
As the washes started to dry, I started to sculpt each little image, adding an accent color, scraping out some whites, throwing in a complimentary color, and splattering, still with no idea what I was making, just having fun and playing around.
Gradually, each painting started to look like something: a dramatic storm on a distant plain, a sunset, a beautiful valley in late afternoon, a brilliant sun peaking out from behind a cloud. It was then that I started to add shapes and colors to help describe and clarify the vision: furrowed rows of a farm field, a grove of trees on a hillside, a distant lake. I finished by adding some strokes and spots of white paint on a few of the scenes for some added interest.