Always carry them in a carry-on. It will be less likely to be lost than checked luggage. Carry-ons and their contents are also less affected by temperature change. The in cabin temperature is less likely to experience extreme temperature fluctuations.

Bring the generic names of any medication that you use, since brand names can vary by area or country.

If possible, carry medications in the original bottles or containers. This helps to minimize security questions.

If you must carry any questionable drugs or large quantities, bring a letter of verification from the doctor allowing you to have and use these drugs.

When traveling outside the United States, always confirm what you can take with you. A legal item in the U.S. may be illegal somewhere else.  At best they could be confiscated or destroyed. At worst, you could be in trouble with the law !

Checked luggage can be easily lost. A well-packed carry-on bag is your safest and most secure bet.

It is the best and only place for your passport, travel documents, itinerary, directions, vouchers and coupons.

All valuables, such as jewelry, electronics, family heirlooms or mementos are safest in that carry-on.

If a converter and/or adapter may be needed, the carry-on is the only smart place to store it.

If you are visiting a country with an unfamiliar language, a dictionary or phrase book should be packed and easily accessible.

One or two copies of a list of everything in your checked baggage. This will save valuable time if you need to fill out a claim form.

A list of addresses and phone numbers of friends, relatives and doctors.

At least one copy of any credit card numbers that you are carrying and contact information for the company.

Copies of any travelers checks and contact information for the bank or vendor who issued them. 

Include a one-night emergency package in your carry-on. That would include anything needed to make it through one night, if your checked baggage is delayed or lost.

Carry a small umbrella, sweater, change of shoes, extra pair of eyeglasses, spare set  of contact lenses, camera, film, batteries, first aid kit, moist towelettes.

Bring a few clothes pins for hotel curtains that don't close.

Pack medications, especially temperature sensitive, in the carry-on.  Keep pills in their original bottles, when possible,  to help lessen security questions.

Tone down the carry-on bag to look "plain". Bright, fancy bags with logos and advertising may seem cool, but they bring attention to you by indicating that something "expensive" may be inside. Less is more !  Don't flaunt it. You could lose it  !.

Carry a number of one and five dollar bills in the carry-on. They will come in handy for skycaps, bus drivers, porters or anyone who requires a small tip.

If not absolutely necessary, leave them safely at home.

Buy and use locks on your luggage.

Try shrink wrap on luggage to not only protect the outside of the bag, but also to safeguard the contents.

Never put valuable items in checked luggage. They are safer in a carry-on bag.

If valuables must be placed in checked luggage, bury them in the lowest part of the bag. That way a quick peak inside won’t give them away.