1. When painting, never judge a value independently but always in relationship to at least two other values. for study purposes only, however, it's perfectly legitimate to isolate a value and seek to determine its individual place on the tonal scale.
2. Always aim for a strong, simple tonal effect rather than for a complex, fragmented one, wich usually serves only to weaken a painting.
3. Be selective, simplify, don't attemp to render all the tones you see, since this is beyond human capacity.
4. Pay special attention to your halftones, they are subtle, delicate creature, and given render loving care and attention they will respons by lending beauty, character and sensitivity to your painting.
5. In painting highligths, pain just what you see, resist the temptation to render them lighter than they are just because they are hightlights.
6. Keep a tight rein on your reflected lights lest they distort the shadow by their overaggressive, deadly attraction. nothing can kill a shadow faster than a gorgeously over stated reflected light.
While value is, for artistic purposes, separated into nine degrees of tonality, it is also-for the same reason-divided into six different kinds. They are: