i am trying to get the walls of the bedroom painted with 2 colors, one being used on the feature wall, which is simple enough when it's just a plain wall.

the problem i have is how to paint the rest of the walls when they're not simply straight up or across with the rectangular air ducts running behind it. so the ceiling is like having a several big blocks attached, so should only the vertical sides being painted, or all surfaces, or just the sides facing down...etc. in order to look descent and proper?

thanks.