Always match your belt with your shoes.
This is a rule that seems to have been abandoned in recent years, but one that the modern gentleman would be wise to reinstate. It also helps to keep things simple, unless of course you really do have rainbow selection of shoes!
For most of us black, brown and tan are the colours of our shoes so it should be simple to match your belt accordingly. It is this attention to detail that will never set you apart when you get it right, but everyone will notice when you get it wrong.