Q: Jennifer, please help! I was inspired by my sister — through an accident. She painted my niece's bedroom with a Frozen them: ice-blue walls and white trim, but the wall paint color ended up being what I thought was a really nice shade of light gray. Of course, my niece hated it. We all pitched in to paint it again, this time, with boring white, and let her pick Frozen-themed bedding, curtains, and accessories. I took some of the original paint home, and the color looks light blue in my bedroom — what my niece wanted but not what I want! How can that happen?

A: Hopefully, you tested the color in just a corner, instead of painting the whole room. Isn't it funny how the same paint can look surprisingly different in two houses? The sunlight, your location, how many trees are around — these are the many things that affect how a color looks, even if the paint is out of the same can. Pale, cool colors such as gray and light blue are great choices for a calm, tranquil bedroom. Just what you need for relaxing and sleep. But sometimes any color, especially gray, can take on different tones. That's why it's so important to spend time with the sample swatches.

Sometimes this difference can be good. I've used the same color in many different houses, including my own, as well as for some clients. A beautiful oyster white is my current favorite. Though the actual color does look slightly different in each house, overall, it's still beautiful.

It's better to prevent surprises before you paint your entire room. Go to your paint stores and collect a bunch of swatches you think you might like. Get some that are a little darker and some a little lighter. Tape them to your walls, and watch how they change over the course of a day, morning to night, and over a few days. Hopefully, the weather will change during this test. Sunlight and rain clouds will also change the color.

Narrow your options by taking down the swatches you definitely don't like. Get more if you need to. Once you've decided on three or four colors you like, invest in a small can of each. Some paint stores sell small pouches of paint for this reason, too. Get the same number of little brushes, as you want to use a clean, dry brush for each color. Paint a large area, maybe two or so feet across, in a corner if you can. Paint each color next to the trim, if possible, and near the floor and the ceiling. A large area helps you see the true color, not just how it looks in comparison to the existing color of your walls.

Again, watch your samples over a few days. Repainting a mistake isn't hard, but it does take time.

Have a design dilemma? Jennifer Adams is an award-winning designer, writer and TV personality. Send your questions to AskJennifer@JenniferAdams.com or on Twitter: @JenniferAdams. For more design ideas, visit Jennifer's blog on her website at www.jenniferadams.com.