Grip strength is always important, especially if you value snatches, cleans, deadlifts and pulls. One method I really like to build a strong grip fast is the Goerner continuous ramp.
Hermann Goerner was a strongman from the early 1900s. Among other things, he deadlifted 730 pounds... with one hand. He also deadlifted 600 pounds with a two-finger grip. Can you imagine the grip strength?
To improve grip strength he used a continuous ramp that went like this:
Goerner Deadlift Ramp
Start by deadlifting using only the index finger of each hand. Do sets of 3 reps adding weight on each set. Work up until you reach the maximum you can handle for 3 reps using one finger per hand.
Continue to add weight, but switch to a two fingers (per hand) grip. Using that grip, again continue ramping to your 3RM.
When you hit your max with a two-finger grip, switch to using three fingers per hand and ramp toward a 3RM again.
Then switch to a regular full grip: double overhand (not a mixed grip) working up to a 3RM. From there you could continue to ramp either using a hook grip or a mixed grip.
This approach will significantly increase grip strength in a very short period of time. You'll see dramatic results in about 4-6 workouts. Use it twice a week for the fastest results.