THE SECRET TO HAPPINESS (according to something I just read on the Internet) -- IS VEGETABLES! I guess you have to actually eat them in order to truly be happy, but we're going to draw and paint them, too.
For these exercises, work "from life", if possible. Visit your local market, grocery store, or farmer's market, and fill your cart or basket with lots of interesting colors and shapes.
Now, try a few, or all, of these exercises/studies -- either in your sketchbook, or on scrap pieces of watercolor paper:
1) PUMPKIN with SCARF -- Set up a pumpkin, with a patterned scarf draped around the base of it. Start with a wet-in-wet underpainting (use warm colors). When that's dry, draw the pumpkin and scarf.
Draw a "frame" behind the pumpkin, and paint a transparent wash over this background shape. Paint the pumpkin and the scarf, adding some darks in the stem, and some cobalt blue washes for the shadows. . .