If you drove after drinking, you already make one mistake, don't turn the night into one of mistakes. Here are a couple of things to remember that may help you.
Short and Sweet. If you are pulled over for a DUI, (and you have been drinking), don't give the police officer anything more than you need to. Hand over your license and registration. Be polite. But as far as telling the officer how many beers you had and when you ate, etc., it only serves to expedite things to a DUI arrest! You are under no legal obligation to answer questions from the officer about what you drank or when you drank. If he want you to do field sobriety tests and you don't think you can pass them, politely decline without giving a reason. You have no legal obligation to do FST's.
Don't be a Smart-Ass
Take an attitude with the officer that pulls you over, and you can rest assured that he's going to make this encounter a memorable one. Trying to argue your way out of a DUI is about as smart an idea as driving drunk in the first place. Most officers will make up their minds on whether they are going to arrest you, based on the first few minutes of talking with you. Blabbing away does two things: 1) it makes the officer get defensive and lean more towards arresting you, 2) It makes you seem more drunk by being overly talkative and argumentative.