I have three colors going right now. Here's what I did -
I paid the big bucks to go in and have panels done on the top and I dyed them kick-you-in-the-teeth-red. I've tried different brands and mostly hate manic panic, am fine with fX, and like color Jams (all these are at Sally Beauty Supply). So that grew out for about... 3 months. Then I bleached the roots (it was like coloring in the lines because it had been done before by a pro that could you know.. see the top of my head and important stuff like that). I dyed the new blonde roots purple, and the red washed out ends Fuscia. I kept that look for about... 4 months? I just recently did it again (the bleach the dye yada etc) and went with Teal to purple to fuscia fade. But the fuscia is having a hard time holding on with all that blue based dye, so i'm getting kind of a teal to purple to violet. It's VERY peacock.
I recolor every 3 weeks or so - or when I just can't take it anymore because I'll get LAZY and let it look like NASTY! My hair is shoulder length. There's a pic of it down on my actual profile.
Oh, and I'm Kiki! Nice to meetcha!