First, lets look at a color wheel.
Complementary Colors: Find colors that are in the same family. If you want to wear red and pink that's ok, but make sure they are a complementary red and pink. mixing your warms and cools can often result in a crazy appearance.
Opposites Attract: We know this is true with couples it is also true with colors. Look at that same color wheel and then understand that the opposite side can match. Blue and Orange, Red and Green, Yellow and Purple...the list goes on. Don't be afraid to pair colors and even prints. Feel free to choose a simple understated pattern with a bold pattern. Don't worry they still go.
Neutrals go with EVERYTHING: Its true! Don't be afraid to pair your neutrals up. Where black with brown, the leopard does it and SO CAN YOU! You CAN mix your metallic, they are neutral. there are no rules with neutrals.