Here is what I do if I finish a whole room:
1. Carefully sweep up majority of dust, trying not to create a dust cloud.
2. Shut the doors to the room and open the window and remove the screen. Then put a big fan in the window blowing out. I then sweep up vigorously to lift the fine dust that then gets blown out the window.
3. After things settle, use damp mop and rags to wipe down everything.
4. After a day or two you can then go over with a vacuum or mop some more, but not much will be left.
For a small repair, I simply mop up and vacuum. My drywall taping method (http://www.drywallinfo.com
) uses no sanding until all coats are on, so very little dust is created. Still, if you are cutting drywall for a whole room, you create dust from the cutting.