If you like painting floral subjects, Janet Whittle's method may be of interest to you.
Starting with masked subject areas and dropping in pure colors, Whittle creates a lively, mottled background and then goes on to paint negative spaces around leaves and background flowers. This gives the effect of distant leaves and petals in shadow. Then the main flowers are painted in, dropping colors into the center, shadowing petals and adding detail to stamens, pistils and other structures.
The good thing about this technique is it makes effective bouquet subjects. The bad thing is that the technique leads to somewhat of a sameness to every painting. In this book, the author adds vases, pots and other subjects to the still life, which helps. If you have this book, you probably don't need any of the others as this one is more comprehensive. I don't feel inspired to copy this technique, but there are worthwhile tips to absorb in handling iris especially.