I thought I would show the process for doing the background for the 'Suspend' card from my creativity deck. I struggle a bit with backgrounds because I usually do the main figure first (and I work small) and then need to put in the background later. This time, I decided to do the background separate and then put the two images together in GIMP.
So I did the background and kept it quite light and subtle. Then I added a transparent layer to the initial image and put the two together using GIMP and MyPaint.