Holding your penis, firmly press the skin back into your body by placing both thumbs, nails touching, over the shaft and your remaining fingers underneath for support. Be sure not to cut off circulation to the penis. Hold for 10 seconds then relax and repeat. You want to maintain a continuous pump action. The farther back the penis is held, the better your results will be. Repeat once or twice daily for five minutes. This exercise can also be performed while semi-erect.
Consider ginkgo biloba. This herb is often taken to boost memory, but it also help with blood circulation and may enhance blood flow to the penis. According to a study conducted at the University of California, ginkgo is most effective at helping men on anti-depressants that can lead to sexual dysfunction. Another study found that gingko had no effect. Scientific data is inconclusive, but since gingko enhances memory and has relatively few side effects, it might be worth a try.
The vacuum pump. This is a cylinder that sucks out air. You stick your penis in and the resulting vacuum draws extra blood into it, making it erect and a little bigger. You then clamp off the penis with a tight ring -- like a tourniquet -- to keep the blood from leaking back into your body. What are the drawbacks? The effect only lasts as long as you have the ring on. Using it for more than 20 to 30 minutes can cause tissue damage. This is sometimes used as a treatment for erectile dysfunction, but has not been proven to actually increase the size of the penis.