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
Learn how to read the contour of the green, the grain and the terrain around the green
Slices occur only because your clubface is open at impact, there are several reasons why this must happen but your object should be to assure that the back of your left hand is square to the target at impact