for your knees dipping think of keeping your chin up. not to much but make yourself look down on the ball and try not to move your head during swing. For the left arm straight id stick your right arm out straight at shoulder height Then hold your club with your left hand and take swings and on the downswing it makes you straighten your left arm out. oh and don't expect great control over the club to be able to hit the ball with just your left arm. Aim will be way off but the drill will still work...
