This has been a good exercise for me lately, as I have been feeling overwhelmed and stuck. This gives me a chance to be creative without pressure. I have been doing all of these on the iPad, because it is the easiest tool to just get started and to come back to if I get interrupted.

I've been playing around with a couple of color palettes. This one has been my favorite so far.

I spent way too much time on this one, making sure that there was a fairly even distribution of colors and obsessing over the shadows and highlights.

I liked combining lines with solid color on this one.
And this was a nice start to the whole thing. Simple, yet it gets my creative juices flowing.