From Coral Nafie, former About.com Guide
The tips here will really help you if you feel stumped by this important choice. After all, the paint color will set the tone for the room.
It's great to collect paint chips when planning a room, but hold off making final choices until you've developed an overall room scheme. Paint is available in literally an infinite array of colors and is the most versatile element of your room decor, the easiest to change, and the least expensive. Get ideas but make the final decision after rugs, wallpaper, and fabrics are finalized.
Coordinate Decorating Samples
When you go shopping, you'll need to refer to your fabric, carpet, tile, wallpaper, and trim samples constantly. Be sure to take everything with you wherever you go. No tellng where you might see something wonderful.
Really Study the Colors
You'll find clues about the underlying tones of different shades of a color on a full sample strip of coordinated colors. Even if you're not even considering using a darker tone, look at all the colors carefully. Decide if the family of colors is the direction you're headed with your color selection.
Tried and True Formula for Colors
If you're working with a print fabric, you'll probably be happier if you select the coordinating wall paint color from the background of the print. Use the deeper or brighter tones for accents throughout the room or adjacent spaces. Learn more tips here about how to choose a color scheme.
Trim it Out
More often than not, you'll select a shade of white or off-white for the moldings, doors, and windows. If you're feeling brave, consider the palest shade of color to coordinate with the walls. For a really striking look, try lighter walls and dark tones or bright color for trim.
Consider which paint finish might be best for your project. Matte or flat finishes hide wall imperfections, but glossier finishes will reflect more light.
If you're searching for the perfect paint, the tips here will be helpful.
Warm or Cool?
Colors are often referred to as "warm" and "cool." Orange, red, and pink are considered "warm" colors, while blues, greens, and violet are thought to be "cool." Knowing the theory behind color can help you select the right tone for the feel you're trying to achieve.
White is Not Always White
Trying to find the perfect white can be a challenge! Beiges and off-whites have subtle color, so compare paint chips to your fabrics and flooring to determine if a warmer pinkish or yellow-toned white -- or a cooler, bluer white -- is best for your room.
Keep Notes as You Shop
It's a good idea to make a note on the back of the paint color cards, telling yourself the name of the store where you picked it up, and the paint brand whenever this information isn't printed there already. Since most home centers and hardware stores carry more than one brand of paint, you may discover the perfect color, and then find you can't remember where you got the sample! Then you'll have to start over. Ugh!
Shed a Little Light
The best way to get a true view of a paint color is to look at it in many lights. Take the paint chip outside to see it in natural light. Look at in under an incandescent and fluorescent light. Best yet, take the paint chip, fabrics, and accessories to the room in which they'll live. Check out the colors there.
Measuring Works Magic
Take your room measurements with you to the paint store or home center. The professional at the store will help you determine the correct quantity of paint to buy for your job. Or you might use your numbers to consult one of the handy online paint estimators to get an idea of how much paint you'll need for your project. Remember primer and trim paints.
Ask, Ask, Ask!
For helpful paint advice, go both online and to your local paint store. Tell the paint professional about your project and goals for your decorating project. Ask which paint products they recommend, and why. Get information on specialty paints such as low-odor, stain-killing primers, chalkboard paint, washable paint, and many more.
Custom Color Matching
If you want to achieve a perfect match or find a truly unique color, your paint store or home center offers custom color mixing. This makes it possible to bring in a fabric swatch, painting, or other color reference, and have a paint color created to be a perfect match. Visit Home Depot or Lowe's or call a local hardware store to inquire.
Light colors are usualy most pleasing for a ceiling, because ceilings are seen in shadow. If you'd like the ceiling to match the wall color, buy ceiling paint one or two shades lighter than the wall color (on its color chip). Or, dilute your wall color with white paint in a ratio of 25% color to 75% white.
Try it on for Size
When you think that you've really chosen your perfect color, buy a pint of paint to do a test patch. This will prove to be excellent insurance for less than $10.00. Paint a 12-48" square on a board or directly on your wall. Look at it during the day, morning, evening, and night. How does it look with with the room's flooring, wallcoverings, and fabric choices? If it isn't right, get another pint and try again. We like to test three colors at once to save time. You'll undoubtedly find the right color.
See the Plane
For the most accurate color representation, view paint samples vertically (up against the wall) and view carpet samples set flat on the floor. If you do this, you'll see how the colors will look when they're applied to your space.
Once you've gotten your test sample up on the wall, notice whether the color you're testing might be adversly affected by other colors in a room. For example, if your room is currently painted pink and your test patch is beige, it is likely that the pink will reflect onto the beige, changing the color. The same would go for blue or yellow. Or if there are colored curtains on the windows, their color will reflect onto your new paint. To get the best idea of how the room will look. place the painted sample up on the wall and place the flooring samples on the floor. Test the color in a room with the same exposure to sunlight. Find a room that is neutral.
Let It Dry
Wet paint color often looks different from dry paint. Don't panic when you first see the paint applied to the wall. Let it dry, then check it with your other samples (fabric, tiles, carpet) to decide if it looks right. Paint can also look out of place in an empty room. Bring in a few room elements (a chair, painting, or window treatment) to see how it all works together.
Always Have White Around
Having some extra white paint, carefully sealed in a container, can never hurt. Use it to lighten some paint that's too dark. Or use it to dilute your wall color by 3/4 for use on the ceiling. Just make sure to use the same kind of paint (flat latex for example), mix thoroughly, and make enough of the new color to finish the project. It will be impossible to mix up more later.
Getting used to a new room color might take a few days. A new bold color may seem overwhelming at first. Put some furniture, flooring, and fabric in the room. You'll probably be pleasantly surprised to see that your new color harmonizes with other room elements.