Hi, I'm Pays164, and here are some graffiti coloring tips. When you're breaking down a basic graffiti piece, you're going to have your outline color, an inner outline color, an outer outline color and at least three fill-in colors. So, a good six colors total. Choose three colors that will compliment each other on a lighter tone. That way you can come back with a darker outline and an even brighter inner outline.
For example, I can work a piece that is dark blue, light blue to a light purple. Outline it in black and come back and pop it off with a bright white or even a lime green inner outline. It's just a combination of mixtures of colors that compliment each other and still having that one color that's a little off, like the lime green that set off all the blues and set off all the blacks. With six colors picked out, if that's too much for you to get on and do all at one time. You can break that down in half and work with three.
A good example would be, a silver fill-in with a dark burgundy outline and a white inner outline. Same thing; you have this color on the inside that is a good, solid color that bases the whole piece. The red compliments it and all of a sudden the white comes in as a shocking color to set it off and make it pop.
Personally, I like to work with warm tones, satin tones and earthy tones. I'll use a combination of browns and greens. Avocado green with wasabi green and do a dark plum outline. But, same situation, use a really bright orange. Something really nice to give glares and highlights and inner and outer outlines it make it really pop off the wall or off whatever I'm painting.