You can heat them in a low oven and attach different "architecture" to them with polymer clay. You can heat them with a heat gun (like paper artists use for heat embossing) and cut them like butter! You can heat them and pierce them (Goth Munnys). You can use adhesive and attach paper, fabrics, fiber and clay....
What can't you do?
To make it less intimidating, try copying the blank template (above) and sketching in some ideas... The proportions make it easy to plan shapes and ideas.
Here, using acrylic paints, I made Herman. The first thing I did was pop off the arms and head (use a twisting motion) and I washed it with a coarse washcloth & a drop of dish soap. You should wash it and/or sand it lightly with very fine grit sandpaper or even a piece of denim. This roughs up the surface slightly, prepping it for paint.
Then go to town!
Think in layers, rather than trying to get full coverage with one stroke. Be patient (almost impossible for me) and let each layer dry. Work on it until you are satisfied. Reattach arms and head, do any touch ups that are necessary and let dry.
Spray with sealant- I used a gloss for that shiny look, but chose a matte finish if you prefer. Let dry, give it a few coats as needed....
Allie made these creatures, like MUNNY's but made of hard plastic instead of soft vinyl. Like MUNNYs these are sold "nude" or all white and you can embellish anyway you like.
Allie did these with Sharpies, lots of colors. After they dried, we sealed them with a gloss finish.