Thanks Gamera! I have good results with spray cans by doing the following.
1. Shake the can for two minutes.
2. Hold the model at arm's length.
3. Keep the can 12-18 inches away from the model.
4. Lightly spray the model with a series of 1/2-second shots, covering it with a patchwork of spots, rather than trying to cover the whole model with a continuous spray.
5. Build up a solid, uniform color in two or more sessions, rather than trying to do it with one coat.
6. Use a white primer under yellow.