With Shimano SPDs, use the Multi-Directional Release cleats, SH-56. My wife loves them as they are easier to unclip as they can release upwards too. The standard ones are SH-51 and only release sideways. Aggressive riders might risk unintentional release with the SH-56s though. Something that helps too is saying out loud when stopping, "unclip left (or right)" this will help train you to make conscious movement when unclipping. Of course, you may still have unexpected tumbles--we all do even after years of riding.