Here is a fun drawing exercise from Keys to Drawing with Imagination by Bert Dodson: Use an idea from one drawing to trigger an idea for a new drawing. Draw from imagination and keep the drawings simple, without backgrounds. For example, in the sequence below, I start with something with branches: A tree. That made me think of something with many legs: An octopus. That made me think of something with many feet: A centipede. That made me think of many shoes.