Another thing I love to do before I actually start to colour an image is to mark the spots where shadows should be or particular highlights, keeping the light source(s) in mind. It helps a lot later on when colouring.
For this image I wanted to have three different light sources which emit an irregular glow (bracelets, orb). I marked those three objects and where some coloured glow should be seen with a pink fineliner. Yellow stands for the rest of the shadows that still follow those light sources. Well, and green stands for the darker parts in the hair. Single strands of hair are not important!
It doesn't really matter what colours you use but they should be easily visible; never mind strange colour compositions as long as you know what they stand for.
Again: Don't use the outlines for this!