Even if you are in the camp of paint being the last thing to implement, yet it should be part of the process from the beginning. Paint is a simple thing to change. After you invest in reupholstering a sofa or in that expensive custom window treatment you committed to, paint should be the last thing you apply, as you can repaint at any time (in most cases). So if you’re starting from scratch, have an idea of what colour you want the walls to be, but wait until the big components are in place before you pick a specific hue.