Grip strength is everything, especially in grappling and fighting sports. The key to grip strength comes in a wide variety of techniques.
- crushing grip
- wrist flexion and extension
- ulnar and radial flexion
- pronator and supinator muscles
Just to name a few ways to train them. You can also use fat grips and many different types of grips available with specialized equipment.
The best tip I can give you is train them every day with different grip varieties.