In my opinion, forearms and hands are some of the most underrated muscles in the body.  Though grip strength training, hand strengthening and forearm exercises are unlikely to help you build massive new muscles, they will promote an increase in functional strength.  General forearm strength is required for a number of different lifts.  Anyone with weak forearms may be limited in their ability to perform lifts.  Additionally, once you start doing forearm exercises, you might be surprised to find that your other lifts actually improve.   Hand and grip strength can help with everything from a simple activity like carrying a suitcase to any number of sports such as wrestling, martial arts, football, and baseball.

Improving the strength of your forearms can improve your ability to perform other types of lifts. As an illustration, it is difficult to perform deadlifts and pull ups if you are unable to hold onto the bar itself. In order to strengthen your forearms you will need to add in some exercises to your routine that emphasize a pulling motion. But, you may realize even greater results if you include other types of forearm movements in your regimen.

When I work my forearm muscles I will usually do about 10 repetitions per exercise.  This is one area of strength training that I think benefits from a slight endurance approach.  Forearm exercises will help to increase your overall functional strength as a means of improving lifts and other related training exercises, however you should also give some focus to strength training of your hands and your overall ability to grip.

In my opinion, people can have strong forearms without having strong hands, but can't have strong hands without having strong forearms.   Grip strength training should help improve both hand strength and forearm strength.  

To properly train your hands, you should try to include training for each specific grip type.   For pinch grip strength, you can hold a heavy object such as a weight plate (or two weight plates) between your thumb and fingers.   Supporting grip strength is attained by holding really heavy objects, such as dumbbells, in your hands or alternatively hanging from a pull up bar.  If you wrap rubber bands tightly around your fingers and work to open and close your hand against the tension that is created, you will be training what is known as your "extensor" muscles.

For crushing grip strength, you'll need hand grippers.  Regrettably, many of the commercially available models are flimsy and meant for high repetition use. The same effect could be achieved by attempting to squash a tennis ball in your hand. Make sure you go out of your way to find Heavy Grips or Captains of Crush in order to get a truly beneficial strength training workout for your hands. They are products meant for hardcore strength trainers, and you will never lack a challenge, because these grippers offer 350+ lbs of torque resistance. Though I need not articulate a complete workout here, you can always rely on the inverted squeeze, the standard squeeze, and negative squeezes in which you compress the gripper as tightly and for as long a period as possible. Since hands do not require significant recovery time, it is possible to do these routines 4-5 times weekly. However, I will usually only do this 3 days each week in order to maintain a full day of rest from training.

Anyone who has yet to try grip strength training, hand strength, and forearm exercises should really make an effort to incorporate such movements into their regimen.  Stronger hands will help you with pulling exercises and help you gain functional strength.  Perhaps you will even reach a point where your ability rivals that of Bruce Lee. To see how functional your forearm, hand and grip strength is, just try carrying a 60+ pound suitcase through an airport - without using the wheels.