This is something I leave to the professionals. I've not overly vain about my hair, but I'd be so upset if it ended up being a weird color. That said, I get highlights about twice a year. They're too expensive to maintain more frequently. I otherwise get all-over color that's about half a shade lighter than my natural color about every 12-13 weeks (I have dark hair with a lot of grey around my face). When that color first goes on, you can't really see the highlights much anymore, but as that top color fades, the highlights start to come out again, although they're more subtle. I usually get a lot of compliments--especially when I'm in the sun--when the color is at that stage because it looks more natural than fresh highlights (at least on me).