With a correct grip, your racquet becomes an extension of your arm. A proper grip aligns your racquet parallel to the front wall at impact with the ball.
The backhand grip is different from the forehand grip as discussed in this video. This is a very important point and one of the most common reasons why many players have trouble with the backhand stroke.
Also, please do not strangle the racquet with an overly tight grip. You only need to hold the racquet with enough pressure to keep it from flying out of your hand. So relax your grip!