Get better acquainted with colour theory by doing some quick abstracts using different media. Each one has a different result when you mix or overlay different hues. It’s a great way to discover different colour combinations for more serious studies.
Try doing some cloud studies in different media, you’d be in good company if you did; Turner dedicated whole sketchbooks to it.
Instead of using the whole of the brush for painting in watercolour, or anything else, try drawing with just the tip of the brush.