One of the exercises my teacher made us do was to collect a natural object, then experiment in techniques and media that we wouldn't usually have used.
I picked up a piece of bark from our field.
First, I drew it, but not in my usual, photo-realistic style. I used cross hatching to create detail and texture. Personally, I think it strikes a particular resemblance to a whale, but others said it looked ok.
Then, after tracing the image onto a second piece of paper, I used torn bits of sugar paper to collage the image. I hated it. The colours were too bright, it looked too abstract... Then I slid the tracing paper across it accidentally, and realised it actually made it better. It's translucent nature dimmed the colours,and the lines I had used for tracing gave it definition. I offset it, so the sugar paper is still visible, but it gives it more character.
This is a particularly bad photo of the final technique I used. I applied layers and layers of different shades of brown paint to the paper, before using the tip of a blunt pencil to scratch in the details of the bark pattern. This is called sgraffito, and it worked rather well.
Clustered together, I use these three experiments as a reminder to step out of my comfort zone every once in a while, and try something new.