Make sure you know which vaccines you need. It can be very specific with respect to region, city, length of time and nature of the visit (cruise ship passenger vs helping on a farm for example). You can try going to your primary physician but we've found good success with a Travel Medicine specialist which is much more likely to have the required vaccines on hand. They can also give you advice on food and water safety, jet lag, mosquito precautions and other maladies.
Speaking of Jet lag...some people do well with sleeping pills while others use melatonin. Some just get through the jet lag themselves. Check out the article Jet Lag: What it is and how to beat it.