Many players release incorrectly because they can not physically produce the internal rotation of the hip needed in the downswing and release, use this quick half minute stretch before playing to work on your hip flexibility and allow your body to make the proper swing
Learning how to judge the speed of a putt is a developed skill which can be improved with a simple drill like this one
Breaking putts can only enter the hole in a limited area; by imagining the hole with a piece cut out you can envision the area of entry