I'm finding it increasingly important to create a value sketch for my paintings before I actually begin painting. This means that if I'm working from a photo I will turn it into a black and white image and then paint that first, so that I can see a light and dark pattern. If I'm working from life I will do the same thing and create a monochromatic study of the scene, getting my light, dark and gray values in place first. This is SO important! Once you've got your values down you can then plug in almost any color into a particular area of your painting-as long as it reads correctly a far as VALUE is concerned. Ask yourself: Is a particular color note that you're going to put down of a light, dark or medium gray value or perhaps really black?
The following is a painting I did using a photo as reference in Painter X3, entitled FOREST FLOOR. First I've posted the original photograph, then comes the black and white oil sketch and then the finished painting:
ORIGINAL IMAGE
VALUE OIL SKETCH
FINAL PAINTING
