I feel it might be re-hashing a whole lot of stuff that other poeple have gone on and on about over the years.
They've talked about the importance of colour and I have ignored the advice every time.
Recently though I smartened up.
I was going through Nick Cross' Blog reading about his process after watching his fantastic short - Pig Farmer
He mentions to, "Never underestimate the value of using gray." It finally got me thinking hard about how I paint and use colour.
So I created a palette with a whole lot of grey values, and threw in more saturated versions and other tones.
It has made a world of difference. Until you start working with greys, you don't realize how colourful they can actually be. What's more, when you add a more saturated value over top, you can start to play light more easily, direct the eye better, make your image more dynamic and create interest.
I, personally feel that it has made a big difference in my paintings already. As I become more comfortable it, I can only get better at it.