It appears that all the pertinent points of attaining, and using proper back tension have been well covered; but I'd like to add two items that I haven't seen mentioned:
1) There should only be two areas of muscular tension in your drawing arm when at full draw: 1) the muscles holding your hook/fingers on the string must be set. 2) Your Back muscles, specifically your rhomboid & trapezius muscles, are under tension holding your draw wt. The rest of your arm should be absolutely relaxed and simply provides the link between your fingers/hook and your back muscles. There should not be any tension in the muscles of your forearm, nor your shoulder.
2)(RH shooter)If, without a bow in your hand, you assume your full draw position, bow arm extended and drawing arm set in the proper aligned position, you can flex/tighten your right trapezius muscle so that your right scapula (chicken wing) moves toward your spine, you're simulating the back tension needed during shot execution. If you'll rotate your head from the normal forward position to the right towards your shoulder while flexing your trapezius muscle, you can actually watch your elbow move towards the center of your back.
It's virtually impossible to pluck your string if you use this action during shot execution; and your release hand will end up moving straight back to your shoulder, as has been noted by several above.
While it does take concentration to train yourself to use your back rather than your arm and shoulder muscles, you'll find the effort very worthwhile both in more shot consistency, as well as less muscle fatigue. Them back muscles are larger and stronger than your arm muscles.
Never a dull Moment in Trad Archery!