How do you attache your leather cuffs to things?

Depends on the situation. We've used everything from a short leather dog leash to fabric scarves. If I want both of his hands over his head on the bed, I usually attach the leather cuff's rings together with a carabineer and then use a pair of metal handcuffs to attach them to the bedpost (1 cuff on the carabineer, one on the post).