Collect or exchange as much small change as practical, very few people seem to have change, especially in rural areas.
Take a fair amount of small denomination US money for airport (departure) taxes and when you only need to exchange a small amount of money-like when leaving a country. You can also often get better prices in shops if you pay with greenbacks.
In general, cash is better than traveler's checks. Cash can be easier and quicker to exchange and command a higher rate or the commission can be lower. In some places, the larger the denomination of bills, the better the exchange rate. Many merchants will take dollars and their rate of exchange can be higher than the "official" rate.
Refer to your guide book on the existence of any black market for currency exchange and whether to or how to use it. Some countries are more tolerant of black markets than others.
When you exchange money, exchange as much as you think you will need for some time as it can be a real time consuming task or the banks will have odd (and short) hours. You may not be able to exchange money at all in small towns or in the countryside. Money can also be exchanged in many hotels.
Take a personal check and an American Express card. If you need more money, you can go into an American Express office with your card and write a check for traveler's checks. Cash machines are also more common now in large cities.
Keep money and valuables in a money belt or pouch under your clothes. If you carry a bag for guide books, maps, brochures, etc., use one with a zipper and hang on to it. Leave your wallet and purse at home. Crimes that take place are usually crimes of opportunity, like pickpockets, as opposed to violent crime (unlike in the U.S. According to FBI statistics from more than 80 other countries, only the Bahamas has a higher than the U.S. per capita frequency of robberies and violent thefts).
Unless you have an audience with the head of state, leave all jewelry (and engagement ring) at home.
ALWAYS keep your passport, plane ticket, money and camera with you.
If something doesn't't go right, smile and be persistent in what you want. Getting mad, yelling or fist pounding will only be met with resistance.
As soon as you arrive someplace, arrange your way on to your next stop. trains/planes/("first class") busses tend to get booked up in advance. Travel agencies can usually get reservations for you as they book blocks of seats well in advance.
Arrive early and get aboard early any bus/train/plane etc. They can be oversold and/or fill up in a hurry.
When traveling by regular bus, try to get seated close to the front as they will keep packing people in until there is no room left inside. Additional people then hang on the outside and climb on the roof, when travelling in a ordinary bus.
Always settle on a fare before climbing into an un-metered taxi. If metered, make sure the driver will go by the meter or decide on a price. Make sure the price includes everyone in your party. In some countries, the meters can't be readjusted as fast as the rate of inflation so the fare may be the meter price plus X%. Check your guide book or ask someone if the driver won't go by the meter. Rates are often higher in the middle of the night and between an airport and town.
Reconfirm all airline flights along the way. It is possible to show up for a flight and not have a reservation because you did not reconfirm.
Every time you check in at the airport, check your tickets afterwards and make sure that the agent did not tear out more tickets than she/ he was supposed to.
When you step out the door of an airport, be prepared to become the focal point of dozens of taxi drivers and kids drumming up business for busses. Know what you want to do before stepping through the door. Check your travel guide or ask someone in the airport how much a ride to town should cost and what the choices are.
When you step off the bus or whatever in a new town and need a place to stay, and some kids come up and offer to show you a place, go ahead and use them. You can always take a look and say no. They are just trying to drum up business for someplace and/or a commission for themselves.
When asking directions to someplace, ask several people, and keep asking as you go.
Use a travel alarm clock to wake you up in time for that early morning bus/train/plane.
Medicines of all kinds are usually available in local pharmacies with no prescription necessary. Check expiration dates.
Unless you are in an expensive restaurant, you will be charged for any bread, butter, jam, cheese, olives, etc. on your table that you eat.
Check your guidebook for taxi and restaurant tipping guidelines. In some places the service is included, others it is not, and in still others there is a combination of included service charges and tipping. For tipping 10% of the bill amount is good.
If you wear shoes that can be polished, watch for kids who will sneak up to you, slap some polish on your shoes, then offer to finish the job. Settle on a price first if you decide to proceed.
If you hand out coins to children, you are likely to start a parade.
Above all, use common sense!