Looking for colour
It is often easy to oversimplify areas of colour in our minds. But if you look carefully at any one area of local colour you will find, not only quite a range of variations of tone and hue within that same area but a range of interesting reflected colours. I enjoy looking for these and bringing them out in a painting. It can add a huge amount of life to things that could otherwise feel flat and uninteresting. It also helps in tying elements of your picture together, adding harmony and balance to a composition.
Colour in white
When you look for the very important colours in white and successfully recreate them it can bring your whites to life (not a soap commercial!)First challenge is to let go of the over simplified version of just leaving an area plain white. It will be flat and lifeless. The second challenge is identifying the subtle ranges of colour in shadows and reflected colours (which are much more pronounced on a white surface and so easier to find and more exciting to recreate).