Here's my method which involves a cockring, jelqing and kegels:
1. I use an O-ring (cockring), that can be purchased from any hardware store, that is 1/2 inch smaller then the base of my shaft when hard. I'm 1.8 in diameter so use a 1.25 diameter ring. I've tried 1.5 but it's not quite tight enough. Blood comes into the penis from the center and leaves toward the outer edge so the ring has to be tight enough to hold it in and will have a tendancy to make you super hard and will expand the head to the max.
2. I do Kegels. This is the same exercise women do when they want to tighten their pussy. Basically it's working the muscle that controls urine flow. This is also beneficial for men as it aids in controlling premature ejaculation. You can do these anytime because no one knows you're doing them. I don't know how many I do a day but once you start they get easier. When you develop this muscle it will push the blood into your penis when aroused and wearing a cockring.
3. I jelque my cock once a day. I don't do this for a long period of time, normally I do it in the shower every morning. I use soap for a lube and ordinarily go for about two minutes. I think this keeps the chambers in your penis elastic and also lends itself to increasing penis length. This also will push blood into the head.
4. I'll do a routine I call a "pump-up" that is basically masterbation while wearing the cockring and performing kegels. The kegels push in maximum of blood really increasing the size of the head and the cockring keeps it all in. I'll do this once or twice a week for a half hour to an hour. This really blows up the size of the head (it's like pumping internally). I've had my head expanded so much the skin has split or have developed what looks like stretch marks. This hasn't been serious and after using an ointment like Neosporin it goes away quickly. This makes sense that it does this because if the head is growing something has to give. You know you've accomplished something if, after the session and you're soft, the head is wrinkled.
This has worked well for me. I've increase my lenght by 1.25 from 5.25 to 6.5. I wish I had a previous measurement of my girth ( to compare) but I'm guessing an increase of at least .75 inch. My head is very predominant at 2.5 inches in diameter, side to side, with 7 inches around.
Couple of drawbacks is getting it in for intercourse and putting on a condom. The wife and I use lube but It's still kind of rough but once it's in she loves the size. Although I don't use a condom much I found that rolling it down a bit and then stretching it over the head works. You can't roll down right from the top.
Hope this works for you if you try it. However, don't expect results overnight. I've practiced this over quite a period of time to get these results.