A good color means natural. Look carefully at a fistful of hair in the mirror. See how each strand has a different tone? Perhaps even different colors on one strand? These are the natural striations that Mother Nature gives each head of hair to work with natural lighting. A good "color job" must duplicate these natural highlights to be effective.
Is your hair healthy enough to withstand the chemical onslaught some coloring products produce? Or could it use some TLC before you step up to a new color?