Move furniture out of the room or arrange the furniture in a cluster and cover with plastic dropcloths to protect the furniture from paint drips.
Place plastic dropcloths on the floors.
Scrape away any loose ceiling paint with a putty knife.
Fill a bucket with warm water and don protective goggles.
Wipe down the entire ceiling with a damp sponge to remove dust. Rinse out the sponge when it becomes soiled with gray dust. Removing the dust will prevent poor adhesion, which can cause chunks of popcorn paint to fall. Allow the ceiling to dry.
Perform "the finger test" by swiping your finger across the ceiling's surface. If your finger appears gray or white, wipe the ceiling again and repeat the test until it comes up clean.
Open the can of ceiling paint with a flat-head screwdriver and mix the paint with a wooden stirring stick. Mixing may not be necessary; read the directions on the label to determine if mixing is recommended.
Pour the popcorn ceiling paint--a thick, toothpaste-like paste--into a paint tray or slather onto a hawk--a horizontal metal board with a handle. Immediately replace the cover on the paint can, as the paint is already thick and drying will cause it to thicken even more, making it difficult to handle.
Slather an even layer of paint--approximately 1/4 inch thick--onto a 2-by-2 foot area of ceiling, using a floater. You can use a paintbrush, but it will take much longer and it will be more difficult to apply an even, uniform coat.
Dab the paint with the tip of a large paintbrush, which should be held in a perfectly vertical position during the process to provide maximum contact between the tips of the bristles and the ceiling. This will create the popcorn finish. Create the texture in the center of the painted area, leaving a 2- to 3-inch border of untextured paint around the edges. When you apply the next area of paint, blend the new area of paint with the first 2-by-2-foot patch. If you were to texture the entire area, the edges would be flattened out when you blend the first area of paint with the second 2-by-2-foot area of paint.
Repeat steps 3 and 4 until the ceiling is complete. When working on the area of ceiling near where it meets the wall, it's best to work facing the wall. Working with your back up against the wall can be awkward and lead to neck-cramping.