This one is a little dark because I covered the flash and tried to use the ambient daylight to light the painting so we could see it face on rather than slightly side on. Anyway, you can see the colours starting to appear. I paint it on like a thin wash - a glaze made of liquin and the oil colour. Of course that means waiting for each 'glaze' to dry before applying another. But you can get some lovely subtle colour shading this way. Just like using layers on low opacity in Photoshop.
And more washes of colour.
And once more... waiting for that layer to dry. :~)