There are four keys to the correct grip: placement, positioning, pressure and precision. Check these four things every time and you will have a solid grip
Controling your ball from the rough so that you can actually hit the green requires a steeper swing, gripping down slightly and a tighter grip so that you can keep the clubface square and a minimum of grass between the clubface and the ball
Use this lat stretch to eliminate the need to bend your arms in the backswing and try this over the head hip and torso stretch to increase the separation between your hips and torso to make a more powerful swing