D'Israeli's method is interesting but I'm not nearly precise enough with pencils for it to work well
If I've got a finished ink page I normally have about five layers underneath to mix colours in and one on top of the inks for lighting and other things I want to emphasise.
Within the five underneath, normally one is set aside for actual background tones, one for base colours (that end up as deep shadows and/or what I call 'second inks', two for main colour (one for Balance Adjusting if I start to second guess my initial colour ideas) and the fifth for detail.
This does involve a lot of sodding about but I prefer the painted look to things as opposed to the neat and tidy airbrushed look that most strips seem to have. Plus, across five layers you can afford to experiment without losing other aspects of the colour that you like. This process (in theory), saves the time you might lose when changing colour schemes mid-way through when you decide you're not keen on them anymore. It does occasionally go tits up, mind
