After years of suffering hangovers and trying all sorts of remedies, I can confidently offer these tips:
Cut down or, if possible, totally avoid aerated drinks or club soda. Add only real fruit juice or just plain water to your drink. Have lots of salad along with the drink; cut down on fried stuff.
Try and smoke as few cigarettes as possible.
Drink plenty of water before, during and after imbibing liquor.
Don't mix drinks. Last night I had beer, brandy, rum, beer and brandy (in that order). Urghhh...I felt so bad this morning.
Last tip: Only if you can handle it -- Have a Good Morning peg soon after you wake up, and continue drinking:-))).