don't drink (alcohol) too much before the deed.
one can of beer or a glass of wine should suffice. this will prolong ejaculation whilst maintaining a fairly hard and quick erection.
also get some L-Arginine supplements and horny goat weed to improve blood flow and circulation.
exercise more too! not sex ah, but any cardiovascular workout like jogging, swimming, cycling. you strengthen your heart, you will increase blood flow.