If you're getting rid of your old stucco ceiling, you should make sure there is no asbestos up there before you remove it yourself. If there is asbestos, you need a professional to remove it. Otherwise, proceed.
Cover Your Surfaces
Start by removing all the furniture in the room. Cover the floor or any furniture you couldn't move with plastic. Seal the plastic at the edges. Then, take down the light fixtures and install some temporary lighting if necessary.
Wet the Ceiling
The key to removing stucco ceilings is a damp surface. Spray a small section of the ceiling with ordinary tap water and then pull off that part of the ceiling with a knife or a small scraper. Put enough pressure on the scraper to drag down the damp part of the ceiling. Moisten the next portion of the ceiling and repeat the process. Once you have removed all the stucco in this manner, any damage to the ceiling below the stucco should be filled with caulk and left to dry.