Most people say to put a twist in the middle of the strap strap where it passes through the pedal, but I've found that still slips, even with the stiffest leather straps, and the buckle end keeps getting longer and longer until you have to pull the strap back through. This is how I do it, but you need good long straps, which are hard to find in leather, but the nylon ones at your LBS they use for MTBs are perfect.



The buckle is self-explanatory. You just flick it to loosen the strap. So long as you don't pull them so tight that your feet go to sleep, you'll be able to get your foot out in an emergency.