Start with your bare hands for a couple of months to gain some initial endurance. Find a free penis enlargement book on a torrent. Always start and finish a session by wrapping your penis in a hottish wet hand towel for 2-3 minutes to increase bloodflow and loosen the ligaments in the penis. "Jelqing" (penis milking) is by far the best exercise for both length and girth. I did "hands only" penis enlargement exercises for about 3 years and increased my erect length by 2 inches and my erect girth by 0.5 inches.
Then buy a penis extender for length. I use an "AndroPenis". I've only used it on and off for 6 months and I increased my length by a further 0.5 inches. In my opinion, a penis extender will get you much faster gains. I must add that I didn't follow the instructions. You're supposed to set the extender to a "gentle" length and wear it everyday for 8 hours and slowly increase the length over a year to get an increase of 2-3 inches. However, since I'm familiar with "overload principles" from weight lifting and kickboxing, I set the penis extender to a length where I'm in pain after an 1.5 hours. Then I rest and eat fresh meat and veges for growth.
Also buy an adjustable cockring for girth. Put it on as tight as you can and then jelq your penis. You'll find that after jelqing with a cockring on, your penis will not only become thicker, you're erections will also become amazingly hard (without the cockring on). When you "plateau" with the cock ring, buy some rubber dishwashing gloves and cut the fingers off. Also cut the tips of the fingers off so you have a thick rubber ring. This is your new cock ring. Now jelq with it on. I've increased my girth by a further 0.5 inches with this method.
When you overload your penis, sometimes it will swell up and look like a freakshow. Don't freak out because the swelling will go down in a couple of hours.
Start off light and only a few minutes and then work up to a heavy load for an hour with the jelqing exercises. With the penis extender, follow the instructions. Follow this and you'll gain 1-3 permanent inches in a year.