Before wallpapering the ceiling, make sure it is clean. Apply a special primer specifically made to work with wallpaper. It is designed to reduce the amount of glue damage should the wallpaper ever be removed. Use a standard paint roller to apply the primer.
Determine your vertical start line for the first strip of wallpaper. This is done by measuring the width of the wallpaper then using that measurement to determine the placement of your starting point (usually from a corner). You can use a level, yardstick or a plumb line tool to make the vertical start line.
Measure the distance from one side of the ceiling to the other. Use that measurement to determine the length of wallpaper you’ll need. Add an extra four inches to this measurement so you can match up the wallpaper’s repeating pattern.