I ride at least one horse without stirrups every day. My "official" no stirrups horse (the one I've ridden without stirrups for the last 26 months) is rehabbing from a [suspected] broken rib, so it's had to be one of my harder-to-do-it-on boys. But that's good for me ;)
I keep a journal of every horse, every ride that makes it easy to look back and see what a horse has done for the last 1-4 months. Nothing fancy and I rely heavily on abbreviations that I often struggle to decipher later, but I couldn't keep my guys in shape without it.
I make a point of consciously thinking about my position at least every few strides (this is one of the biggest things that keeps me from rolling my lower back and hunching over the horse).
I try to take lessons with a dressage trainer regularly, though I have to admit that our schedules haven't lined up lately. I'm excited for her to see my boys, though, now that the show season is over and the TB is straighter and more correct (muscle-wise) than ever and the baby WB is starting to look like a horse (instead of a gangly baby).
And not to be underestimated.....I log on here on a regular basis and get more ideas of things I want to do :D
I try to ride as many different horses as possible, regardless of how nice or awful they are. Unless I think a horse is unsafe, I will not turn down a chance to ride someone else's horse when offered.