I don't think anyone already explicitly noted this, but I've learned to hold still AFTER squeezing the shutter release. I find that it's easy to start moving slightly while taking the shot, especially when I'm eager to take another photo or so something else. Just pausing a second or so after shooting has helped prevent me from subconscious movement before I've actually pressed the shutter.
That's called "follow through". Shooters use it too.