This article with comments was terrific - it was so informative. I found the advice useful. It addressed specifics like the condition of the dry wall surfaces, any additional repairs such. pin holes, chalking, smoothing of wall surfaces, absorption of paint and number of coats that may be needed. It should also include insurance coverage, and reflect the clean-up afterwards. Having a written contract with the company's letterhead is a must.
Primer:  While technically not paint or a finish, the use of primer is crucial in interior painting. Failing to use primer on a porous surface, such as wood or concrete, can lead to imperfect paint coatings that could end up peeling away from the walls. Primer is also a must if covering up a darker color, as it will take fewer layers to cover the old paint.
Ideally, you want as much paint on the brush as you can control without making drips or blobs. To do this, Doherty dips his brush about 1 1/2 inches into the paint, then taps (not wipes) each side of the brush against the side of the can. Tapping knocks off the drips and forces the paint into the bristles. "The brush releases the paint just like a fountain pen," he says. Weeks agrees, saying, "Just be sure to keep your brush moving, or it'll start to drip." For more delicate work, such as when you're painting trim or window sash, you'll want less paint on the brush. Doherty again dips and taps his brush, but this time he also scrapes the sides against his can. "The outside bristles are drier and easier to manage," he says, "but there's still plenty of paint on the brush."

There are two common types of paint that are available for interior projects: smooth and durable oil-based paints and lower-VOC latex paint. Latex paints are used in most residential settings as they dry faster and are easier to clean up. Oil-based paints are harder, making them a good option for trims, floors and furnishings. In addition, there are 5 basic finish options that identify the sheen and hardness of paint. Matte finishes have the least sheen. They are great for hiding imperfections in walls and ceilings, but are the hardest to clean. Eggshell and satin finishes provide more reflection and a smoother surface for easier cleaning, while semi and high-gloss paints provide the highest amount of sheen and durability.

The walls must be properly cleaned prior to applying primer or paint. This involves using a mixture of soap and water. Nail holes, chips, cracks or other small imperfections should be filled in and evened with plaster and allowed to dry before the entire surface is lightly sanded down and wiped again. Once the wall is clean and dry, you should apply painter’s tape over surfaces you do not want painted. Be sure not to overlook ceiling corners and edges, baseboards and trims and moldings.

I used to work at Sherwin Williams. The best thing to do is specify that you will purchase your own paint. If the painter objects strenuously, he was plaanning on making money in the ways this article outlines. You might pay a few dollars more for paint, but you will have control of the quality of what goes on your walls. Never skimp on paint quality.

As the homeowner, I've done all of our interior and most of our painting. Whenever you paint, preparation is truly key. Anyone can slap on a coat of paint and call it done. If you want something that looks good and lasts, take the time to clean the walls (also if there is a smoker in the house, nicotine sticks to paint), fill any holes, and take care of any imperfections in the surface. Also, tape off ceilings, door and window frames, and any other place you don't want paint to land. Depending on the size of the room and the number of doors and windows, it might take you 2-3 times the amount of time to prep as to paint. I've never had a contractor paint in my home, but if I did, the first question I'd ask is for a detailed list of how much preparation they would do. If it wouldn't be at least as thorough as mine, I wouldn't hire them. Also, ask about priming before painting, particularly if you're going to cover a darker color with a lighter one. There are now all in one primer/finish paints. If this is not going to be used, ask to have the primer tinted as close to the finish color as you can get.

The graph says the average cost to paint a home interior is $1600; at the high end, $4,000. But for what size home? I'm getting estimates for painting an 1800 square foot townhome in the range of about $6500 - which includes sanding and repainting all doors, and painting all trim, walls and ceilings. What does the range above include and for how big of a home? Thanks.

Home Interior Painter