The DO's:

DO make sure that your immunizations are up-to-date.
Consult with medical professionals who have expertise in foreign travel. Immunizations and prescriptions for preventative medications can help you to stay on your feet and healthy during your trip.

DO get, and keep, yourself organized.
For example, if you'll be visiting a country in which you can't read the language, and you'll be using your credit card to get the best currency rate (which in itself is a good tip), be sure to immediately write on your receipt the date, place, and amount of the items you purchased. That way you'll be able to match them on your credit card statement when it arrives, making your bookkeeping a lot less stressful. And while we're on the subject of languages…

DO learn the language of your destination country.
No, you don't have to become fluent in the two weeks before you get there; that's not the point. But a few key words and phrases would be extremely beneficial to you. The local people will generally be most appreciative that you're at least trying to help them help you. You'll be surprised at just how far mastering a simple phrase like 'thank you' can get you. Besides, the more you know about the local language (even if you're nowhere closeto anything remotely resembling fluency), the more you'll be able to interact with and learn about the people of the area. And isn't that one of the reasons for visiting anyway?

DO carry directions with you while you roam around.
If you'll be visiting a foreign country, be sure to carry withyou a matchbook or postcard with the name and address of your hotel, which you can show to locals or taxi drivers to help you find your way back.

DO make a copy of your passport.
Here's a neat little trick: before leaving home, scan yourpassport and other important documents and e-mail them to yourself at an address that you'll be able to access regardless of where you are in the world. Then, if they're lost or stolen, you'll always be able to show the authorities copies of those important items, and you won't be 'documentless' while the originals are replaced.

…and the DON'Ts:

DON'T drink the water.
Yes, it's a classic cliché, but nevertheless important. If you're in a developing country, do not trust the locals to tell you whether or not the water is safe to drink. This is NOT to imply that they would attempt to trick you. Rather, the point is that for them it probably is safe; but for you, it probably isn't. Water from differing locations contains different microbes, and while the locals may have built up bodily defenses against them, you haven't. The same would be true if they came to your home city and drank the water. Play it safe by drinking only bottled water. Speaking of which…

DON'T accept any water simply because it's bottled.
For instance, if you're in a restaurant, drink only bottled water that you can verify has not been previously opened. Have the waiter open the bottle at your table, so that you can be sure you're not getting local water in a commercial bottle.

DON'T accept your hotel room sight unseen.
If you'll be staying in a developing- or third-world country, check out your hotel room BEFORE you pay for it. What's more, you may also want to make a quick pass through the hotel and grounds before deciding to check in. The accommodations may or may not be up to your standards and tastes.

DON'T compare everything to what you're used to at home.
This includes food, prices, quality, etc. While some things may seem a bit unusual to you, try them anyway – especially the foods – and remember to be friendly and courteous. It'll make the trip much more enlightening and enjoyable for everyone, including yourself. And again, isn't the promise of experiencing new things at least one of the reasons you chose to go there in the first place?

DON'T leave home without travel insurance.
You never know when it may be needed. You could find yourself (or a member of your family) sick, injured, or simply stranded because your travel carrier suddenly went belly up. A well-chosen travel insurance policy can help to avert – or at least minimize – many different types of potential calamities. Travel wisely – travel with insurance.