like everything else, practice.
It also helps to find a release that fits you and your style.
I really like the Scott Mongoose XT - uses a buckle, not velcro, and the length of the release can be adjusted.
I started by NOT using my trigger finger, but my middle finger to pull the trigger. I was initially much smoother this way. Now I use my trigger finger. The point being I had to do something to make me much more conscious about what I was doing while learning to use the release.
Now, my whole focus is around extending my time at full draw and still being able to shoot accurately.
I'd look for a bow that you can draw smoothly and has a pronounced valley and back wall. Don't worry too much about speed. You probably will want a longer brace height, like a 7" - these tend to be more forgiving than a 6" BH.
a good dealer will let you try a bow before you buy it.