Should I paint the light colors of a room first or the dark colors first?

Probably depends upon how much of each color and where you’re going to use them. Generaly speaking, it’s best to paint the light colors first, since they are relatively easy to cover over if need be.

Do the trim first, whichever color it is. That way you can cut up to the trim with a brush.

I’ve noticed, when painting, that dark colors take more coats for good coverage than light colors. You’ll use less paint and get truer results putting the dark on top of the light.

Light first.

I’m quite sure you would place the light paint on first.