Many golfers can not get into a proper set up position and posture because their hamstrings are too tight to allow the straightening of the back, so before you tee off or practice work on stretching out your hamstrings so that you can work the golf swing properly around a straight back
In order for your legs and buttocks to fire correctly during the swing you must increase the circulation in your feet so that they do not inhibit these important muscles
Keeping your right hand on the grip in a neutral positoin allows the clubface to come into impact square, turning that hand in either direction will cause the face to close or open at the top of the backswing