Step 1: Let child choose wall color. My child wanted green, because if the ceiling was going to be blue for the sky, of course the walls needed to be green for the trees. He went with Green Energy, by Behr.
Step 2: Paint walls. Curse the texture on them again, as it makes it really difficult not to get wall paint on the ceiling.
Step 3: Stand back and admire, and cross your fingers that your kid will be so happy with the new wall color, that he forgets all about painting the ceiling and doing clouds and birds.
Step 4: Admire your kid's tenacity and determination.
Step 5: Choose ceiling color. We went with something called something like "blue skies" from Sherwin Williams. It seemed appropriate. Figure that as one gallon was more than enough for all four walls, one quart will be sufficient for the ceiling.
Step 6: Realize that assumption made in step 5 was wrong, and run out of paint 2 hours after paint store closes.
Step 7: Buy more paint, which won't quite match the first quart because you go to Home Depot instead of the local paint store since the local paint store is closed on Sundays and there is no way you are leaving the ceiling 75% done.
Step 8: Rationalize that the sky isn't uniform, and any slight variation is fine, or can be covered up with clouds.
Step 9: Google "how to paint clouds on a ceiling." Watch a few tutorials, and realize that the existing tutorials fall into two camps. First, people who are just winging it, and it's turning out just fine. Second, people who actually know what they are doing, have artistic talent, and whose results I will never be able to duplicate because I lack those two characteristics.
Step 10: Buy paint sponges, mix up various blue and grey paints, and just start dabbing it randomly on the ceiling, forming rough cloud shapes.
Step 11: Curse as small pieces of the sponge break off and land in your eyes.
Step 12: Have child come in to check how things are going, and request a cloud that looks like a creeper from Minecraft. Attempt to fulfill request, but realize that you don't really know what a creeper looks like. Explain to child that finding objects in clouds is more of an exercise in imagination than one in precision.
Step 13: Tape bird stencils to ceiling and try out using the small roller to apply the paint.
Step 14: Go back to old method of dabbing paint on with a stencil brush, after roller causes paint to be pushed behind the stencil, resulting in birds with no heads.
(See the bird on the far right? No head.)
Step 15: Watch child be happy with ceiling.
Step 16: Pretend you can't hear when child asks when you're going to start the trees on the walls.