I have used this technique for over 20 years. I put on new underwear [I wear size 28, Calvin Klein], then tuck a new t-shirt all the way under the briefs so the t-shirt material sticks through. It looks a little weird, but your penis is now touching the t-shirt. Then, with your hands on either side of your penis, pull on the t-shirt. This will make your briefs go up and down and your penis grows nicely. After a short while, your penis will start to pop over the waistband, adding even more sensation. I do this for a few minutes, then stop, then repeat. I bring myself to the edge multiple times over several hours. This also seems to really enhance 'pre-cum' production. When I feel I can't take it anymore, I apply one of the traditional masturbation techniques to fully cum. The 'bed' trick mentioned earlier [in Nov by Jack] works great too if you want a hands-off experience.
A variation on this technique is to wear jeans over the new briefs and t-shirt and pull them off and on several times.