The moment of truth in the golf swing is when the club impacts the ball and using an impact bag will help you get the correct feeling of impact
Check the set up angles of your spine, hips, knees and head in order to get into a power position for a power coil and a power swing
A tension filled grip, especially from having the shaft too much in your palms, will kill your entire swing. It stops your wrists from hinging naturally and then works its way up your arms and into your shoulders and locks up your entire swing.