I feel a bit guilty reading this thread. I should learn to use Photoshop to it's full potentiel.
I usually just have some chocolate, dance around a bit, read some fanfic and comics and somewhere between these things I get a sketch from my artist which I colour in.
I hardly remember what I do or why. I do have vague memories of using filters and layers and fiddling around with colours but it's more instinct and playfullness then planning
I do agree with some of the other posters. Layers are wonderfull wonderfull things and although I don't exactly know what they do I try to put some in anyway. At least one in the beginning which seems to help with the colouring process in some manner

