Your carry on bag is where your medicines belong. Never, never, ever pack your medicines in your checked luggage. And this also goes for eyeglasses and anything else you have that you might panic without.
And along the line of medicines, to help get through customs easily, keep them all in their original container. If it is an unusual medication or has a narcotic in it, bring a letter from your doctor.
Make a copy of the photo page of your passport. Carry extra passport sized photos with you.
Plan on using ATMs. Try to bring as little cash as possible. If you can, bring two credit cards. One you will use and one you will keep in your money pouch, in case of emergency. Call your credit card banks and let them know you’ll be traveling and where and when. Otherwise you could find your purchase denied because the bank doesn’t know you are in Asia, or wherever.
Make a copy of your itinerary with friends and family. Include emergency contact info, copies of passports, tickets, travel insurance policy and any other important documents that you have. If you have a scanner, scan them and email them to yourself. That way you’ll have access to them wherever you are.