Many people say do not mix wine, beer and liquor. Choose a drink and stick with it. Darker or brown liquors may also have more toxins than clear liquors. And you should avoid carbonation because it may allow your body to absorb alcohol quicker.
However, doctors say none of these tips have ever been proven. As far as preventing a hangover by eating a burnt toast to suck up the toxins, this and other treatments have not been scientifically proven.
The best way to prevent a hangover is to not drink or at least drink in moderation. If you do plan on celebrating with alcohol Friday night, plan to have a designated driver or the phone number to get a cab ride home.