Hotel Business Cards so you can always find your way back
Passports
Best way to get cash
Credit Cards and exchange rates
Fraud alerts
Credit card chips
Medicines to bring
Travel Alerts to read
Using Foreign Airline sites to book
Data Roaming woes on cell phones
Google Maps
Unwanted Local currency
International travel
Other tips for International travel:
Spend some time on the US State department website: Traveler's checklist
Get Global Entry and skip the lines at the airport
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.
Prepare electrically: what electrical cords, chargers and converters will you need to buy /bring. Read through this How to Choose Travel Power Adapters article.