Here I am demonstrating my inter-locking grip. The inter-locking grip has the effect of tying the two hands together without causing the either hand to open.
To achieve this grip; Start with a normal left hand grip, except that the forefinger is inserted between the little finger and forth finger of the right hand.
The tip of the left forefinger rests over the back of the knuckle of the little finger of the right hand (Photo 1).
The best type of grip is the one that holds the lower part of the right hand in (Photo 2).