I just wanted to add a little something my instructor had me do yesterday. Granted, I am a teenager and do not have the experience many of you have, so take this with a grain of salt.
For a while, I've been fighting my position (mostly balance as I go through growth spurts). Recently, the reins began to slowly slip through my fingers, due to having too "soft" (incorrect softness) hands. I tried the tape, but I found it made me grip the reins and put too much attention in my hands and not enough in my seat.
Yesterday, my instructor brought out a short crop (bat) and had me hold it under my thumbs, on top of the reins. Not only did it bring my hands together and upright, but my reins stayed short. Turns out I had been slightly collapsing my wrists, which had let the reins out. Having the crop there prevented me from having my hands in an incorrect position and it has helped me find softness through my elbows, rather than by opening my fingers or collapsing my wrists.