After I unclip, but before I actually stop and put my foot down, I keep my unclipped foot in the heel-out position. That prevents accidentally clipping back in, and also lets me easily clip in again if I find I don't need to put a foot down.

Once you get the hang of unclipping from one side, you should practice doing the mirror-image on the other side. It might save you from a fall one day.

And, sometimes when you're about to keel over (failed trackstand, for example), I find locking up my brakes can buy me that extra split second I need to unclip. Not sure how that works.