A. Forehand Grip
For the forehand grip, place the forefinger knuckle anywhere on or between the third and fourth bevel of the handle.
B. Backhand Grip
The correct grip, not strength, affects your ability to use a one-handed backhand. Place the forefinger knuckle on the top bevel for topspin and on the second bevel for backspin. Support the racquet by the throat with the other hand between shots.
C. Two-Handed Backhand GripFor the two-handed backhand grip, take the serve grip by placing your forefinger knuckle on the second bevel. Then place your other hand above it.
That is how to get your tennis grip correctly.