I got an ask about my colouring method like a billion years ago and since i finally have like a solid method for the comic i took some screenshots!! I do all my colouring in photoshop cs6.
I start with picking the colours for the overall mood or atmosphere i want for each panel. usually if the base colour combination of the panels works, then the page will still look good when I lay down the flats.
I then start picking colours. if a colour isnt working for me, I use the colour replacement tool in photoshop (image>adjustments>replace color) this cuts down on time a lot.