what's the rule?

I'm never sure how to paint my fingernails. Okay, that's a lie, I KNOW how to paint them, I just don't know what color to paint them. Should I match them to my toes? (I'm huge on having my toes painted- brights, darks, lights, I do it all...) Is it too matchy matchy if I do? Should toes and fingernails be in the same color family, at least?

I guess I'm asking- what's the rule for painting your fingernails???????????

I'm so confused... I hate not knowing the rules! Or... are there no rules at all?????