Just as driving with anything else, allow yourself the distance to see around.
Tailgating to where you can't have a full view around the offending slower driver and accelerating when you're in the other lane is a piss poor way to pass.
Stay far enough back, pick your break, and accelerate in your lane so you can get around and get back in your lane as quickly as possible.
So, you might have to stay a little further back, but if you're sticking your head out to see around him to begin with, you're already doing it wrong.