Tennis elbow and wrist extensors stretch
Tennis elbow is a very common syndrome that affects manual laborers and racquet sport players. It is usually experienced like pain at the outside of the elbow which can radiate down the forearm. This is often accompanied by the decrease in the grip strength.
This dysfunction involves the muscles located on the outer site of the forearm. These are collectively called wrist extensors and their function is to cock the wrist back. Another important role of this muscle group is to counterbalance the muscles that clench the fist and flex the forearm thus making these movements smooth and well coordinated.
There are numbers of reasons for the tennis elbow. It can be inflammation of the wrist extensors tendons around the elbow, or trigger points in the muscle.
My experience treating patients shows that the best way to treat this dysfunction and to prevent it from reoccurring is to gently stretch the involved muscles few times a day for at least a minute at a time, and to ice the outside of the elbow.
So here’s the stretch:

Extend your arm with the palm facing downward and gently pull your wrist down till you feel a nice comfortable tension along the outer side of your forearm. You can fine tune the stretch by slightly rotating your forearm.
Use very gentle force. If it hurts, you are pulling too hard, back off a bit. Breath and feel muscles relax as you exhale. Hold the stretch for at least a minute.
At the end of the stretch put ice pack over the outside of the elbow and keep it there for about 10 minutes.
Here is a good article on tennis elbow that also has a number of strengthening exercises for the involved muscles.