When I first started hand quilting, I used my ring finger - it's the finger I put a thimble on for hand sewing. I began to get pains in my wrist, so I switched to my middle finger, and had no more pain. Over the years I've read about quilters using their index fingers as well.
I do get pain in my wrist from time to time. The pain is caused by the computer mouse and few machines I use at work. If I'm really busy on the computer I wear a wrist brace at night, and a Handeze glove during the day. It helps keep the pain manageable. If I am quilting, I try to keep my wrist straight, which also helps.