Use spackle to fill nail holes, doorknob impact craters, old curtain hardware holes, bullet holes, etc.

I find spackling to be very easy, probably the most fun part of preparation.

Remove plastic plates over electrical outlets and switches. This is very easy and safe. I usually put masking tape over the switch within to prevent it from catching any drips or errors.

If a switch or outlet looks worn or ugly, switch off the power and wire in a new one. These little fixtures are very cheap, priced between 50 cents and $3, and can greatly improve the look of a room.

If you are afraid or not skilled enough to re-wire a new outlet, consider freshening them up with spray paint and a paper mask.

The completed outlets look great. Buy new plate covers if yours clash, are cracked, worn or ugly. New ones are about 50 cents each.

Dress appropriately
Even if you are slow and careful, you will still get paint on your shirt, and on your pants, and probably on your shoes. My specialties include: ruining pants by kneeling onto a glob of wet paint and dragging my sleeve on the rim of the roller pan. Its just faster to change into some crappy clothes and forget about it.

Oh My God. You Might Be Ready to Paint.

Paint with rollers
Don't even think of painting a room without a roller. Rollers are about 15 times faster than brushes. In addition to the walls themselves, you should plan to paint as much of the trim as possible with rollers.

"Power" Rollers which force paint onto the roller work fine. Some use muscle-power and some have electric pumps. Both kinds work pretty well, especially for bigger jobs. Keep in mind that painting the big flat areas of walls is the easiest part of painting, so they can only help so much.

Paint hard parts first
It doesn't really matter, but I recommend progressing as follows:

1. Paint the ceiling (optional)
2. Paint the trim
3. Paint the walls

Its fun to paint the walls. It is not fun to paint the ceiling. When you start, imbued with enthusiasm and energy, paint the ceiling. Then paint the trim. When you are tired, and a little sick of painting, you will have saved the most fun part for last - painting the walls themselves.

I decided this big closet door is "trim".

Painting the ceiling can be exhausting, because you have to do it over your head. If you are standing on a chair, your legs will tire quickly because your feet will be tensed for balance. Also, unless you are an expert roller-pan placer, you'll have to go up and down continuously to get more paint on your roller.

Although the trim (including doors and cabinets) will have a much smaller surface area and require a smaller quantity of paint, the trim takes time because the surface is complicated and there are more obstacles to avoid.

Where two colors of paint are going to meet at a border, go ahead and paint past the border with the first color. With the second color goes on top, carefully paint right exactly to the border. This will end up being a little faster and it will avoid having a thin unpainted seam between the two new colors.

Clean up as you go
Don't be messy, but don't obsess over every speck. Keep a damp paper towel in your back pocket to whisk up drips before they dry. It puts a hitch in your rhythm, but drips are 3-5 times harder to clean if they dry before you get to them.