Things I learned from my contractor: On painting

1. Paint the ceilings first, then walls, then trim. Be careful, and you don't need to bother with tape.
2. For the cutting-in brush, don't cheap out. Get one that is 3" wide and at least $12-$14.
3. Sand the walls entirely to smooth imperfections and to help the new paint adhere better. He uses sandpaper fixed to a handle (similar to a Swiffer, but sturdier) and scrubs the walls completely.
4. High gloss paint is not recommended because it shows all imperfections. Use semi-gloss for trim.
5. Test coats of paint on previously-painted walls to see if you need primer or not. If you need two coats of paint anyways, you might be able to skip the primer.
6. If you're painting new drywall, you need to use primer first.
7. If you have a stucco ceiling, it is easy to remove with just warm water and a cloth - provided the ceiling was not painted before. Once it's painted, the stucco is sealed on quite well.