Well here's mine anyway, it's a bit different and I think easier.
Star off with a picture u want to colour most commonly black and white

Duplicate this layer and change it's colour either by
Colors>Adjust>Color Balance
or
Colors>Adjust>Hue/Sat./Light.
or
the one I useEffects>Enhance Photo>Manual Color Correction
which looks like this

Colour the whole duplicated layer

And delete the parts that you don't want that colour with you eraser brush

and you end up with something like so.....

repeat with other colourable items in the picture

Add effects e.g Contrast etc

and then ur text to get ur finished picture

I'm open for any :?:s