The most important thing you can do before going out to drink, is eat. Drinking on an empty stomach is a sure recipe for a terrible night, and a terrible hangover the next morning. Before you start drinking its best to eat food which is high on oil. Olive oil is a good idea. Not only because its supposedly better for drinking, but also because its a healthy form of oil. Its also good to eat slow-absorbing food like pasta and meat, in order to keep your stomach padded for a long time.
While you drink, its could be wise to consume some water or non-alcoholic beverages. If this might be too shameful, you can always get OJ and tell everybody you're having a screwdriver, or Apple juice which looks a lot like whiskey.
Most importantly, don't drink too much. In my opinion, a good drinker is not a person who can drink much, but a person who can handle what he drinks. I truely frown upon people who drink too much and then act embarrassingly. One should always remain well mannered, even when he is drunk. So never go over your limits, and know when to stop drinking. Remember you don't look too cool lying on the floor passed out in your own vomit.
Always drink responsibly, and never drive drunk!