Give Him a Wring

This is a great technique you can use with a partner or with some modification you can apply to yourself.

Grip the cock between your two well lubricated hands.  Your upper most hand should include the top of the penis in your grip.  Twist your hands together until your thumbs are pointing in the same direction then twist your hands apart until your thumbs are pointing in opposite directions.  Repeat this stroke, varying speed and grip strength, as appropriate.