Try mixing colours (pastels or paints) to make sunset backgrounds. Think about the silhouettes of the living things you might see in a desert/safari habitat. Try to draw these freehand or trace from books. You might even have miniature toys that you could use outside and make their shadow using sunlight and plain white paper, then draw around the shadow.
You could try creating other habitats, using blues, whites and greys to create an arctic scene.