There's a ted talk on this. Yes, really.

The trick is how the bow lines up on the shoe after you're done --you want it to be perpendicular to the length of the show, not parallel. If the bow is running parallel to your shoe, then there are two solutions. Either

1. At the very beginning when you choose between going "right over left" or "left over right", switch from whatever you're currently doing to the other option, or
2. When you go "round the loop" one way, go the other way.

Only change one of these things (if you change both, the changes will cancel each-other out), and the bow will now line up perpendicular to the shoe and come undone less often.