Hang the drywall. Starting against the longest wall, Begin hanging the drywall across the ceiling joists (figure B). Screw the drywall to the joists using 1-5/8 inch drywall screws every 8 inches along the perimeter and 16 inches in the field. Cut the holes for the ceiling lights using a circle cutter and jab saw, or a roto-tool with drywall attachment.Tape and block. Slightly thin your joint compound ("mud") by mixing in a little water. This will smooth the mud and remove any air bubbles. Start taping the joints by spreading a thick layer of mud over the crack, then setting in your tape. Draw the drywall knife over the tape to remove excess, and continue to the end of the joint. Do all joints, and cover the screw-heads (blocking)
Inside corners. For inside corners, after taping the joint and removing the excess, finish one side, let dry, and do the other. Trying to hit both sides of an inside corner at the same time will always mess it up.
Finish. After the mud has dried, scrape with a 12-inch knife to remove any ridges, and sand any really rough spots. Then, skim over every joint with a 12-inch knife and mud. Using the 12-inch knife will help feather out the mud to avoid any noticeable seams.
Sand, prime and paint. After the second (and third, if necessary) coats have dried, sand the seams smooth using a drywall sander and a sanding pole. Then prime and paint to finish the ceiling project.