These tips will help you achieve longer lasting & harder erections:
Stick to a low-fat, high-fiber diet. High levels of cholesterol can actually clog the blood vessels in your penis. This also can cause impotence. Furthermore, you should include a little zinc in your diet. Foods containing zinc include lean beef, turkey, cereal, lamb, crabmeat and oysters.
Make sure you get plenty of exercise. When you're out of shape, not only does this negatively affect your ability to have sex, it increases the likelihood of erection problems.
Stop smoking. Besides the obvious health risks of smoking, studies show that smoking plays a major role in erectile & impotence problems among men.
Finally, the best piece of advice that can be given (and one you probably won't have any problem with) is this: If you want to have better erections- Have MORE erections! The muscle tissue in your penis needs oxygen to survive. Where does it get that oxygen? From the red blood cells flowing in the blood. The more blood that circulates, the less chance of erectile failure. Since blood flows to the penis at a much greater rate when you have an erection, the best way to keep the muscle tissue in your penis properly oxygenated is by having more erections. There, now you have a legitimate excuse to masturbate.
"Place your thumb on the top of the penis at the root and your index finger at the bottom of the penis at the root. Take a deep breath and while holding, squeeze and grip the shaft of your penis in a wave toward the tip of the penis. The thumb, the index finger and the pinky finger push, forcing blood into the penis head. Now hold this grip for as long as you're able to hold your breath. Repeat this exercise 9 times. Each time you hold your breath, count to 9 and with each count, squeeze more toward the head of the penis."