Cut out a variety of colored paper shapes -- circles, triangles, squares, quarter moons and long thin oblongs -- into different sizes. Bigger shapes work well for the face and a hat. Cut smaller shapes that will work well for eyes, eyebrows, a nose and a mouth.
Spread the shapes out in front of you. Play with the shapes and see what sorts of clown designs you can create. If you don't like the square head with round eyes, try a circle with two little triangles instead. Try adding a triangle to the top of the head for a hat, and place a small circle on its tip for a pompom.
Experiment with whether you want to stick to a clown face or if you will include the body as well. The long oblong shapes could either be arms and legs or ears and eyebrows.
Glue the designs you like best to a separate sheet of paper. Hang on the fridge.