So many times this is where it all goes wrong!!
If you are doing a complete remodel, choose your paint color last! Pick all of the other things first (drapes, carpet, furniture).
Always, always, always put up a sample of your paint before you commit to the color. You will be amazed how different it will look when it is on the wall.
If it is the exterior of your house, put up samples in multiple places. Look at it in the morning, day, and evening. The sun or lack of will make the color appear different.
When you have what you want then proceed with the work!!