Pinch block training is great way to improve grip strength since pinching is the crushing action we always speak of in climbing.
Without bothering you with all the theory of pinch training here is a basic exercise to get you strong and crushing.
Using one or two pinch blocks with a loading pin or 60cm sling and carabiner, connect the weight you intend to lift up to the pinch block ring (start with less than 15kg).
Using Club Strong chalk if needed, grasp the pinch block from the top as you pick the block up, hold weights off the ground for 8 seconds and lower back to the ground. Have a one minute rest; repeat for 3 sets