This tips I get from a US website for US citizens. But I think it is also useful for you guys who read it. I edit it a little bit.
1. Sign passport, and fill in the emergency information
--> Make sure you have a signed, valid passport, and a visa, if required, and fill in the emergency information page of your passport.
2. Leave copies of itinerary and passport data page
--> Leave copies of your itinerary, passport data page and visas with family or friends, so you can be contacted in case of an emergency.
3. Check your overseas medical insurance coverage
--> Ask your medical insurance company if your policy applies overseas, and if it covers emergency expenses such as medical evacuation. If it does not, consider supplemental insurance.
4. Familiarize yourself with local conditions and laws
--> I think it is so important, remember you are not in your own country.
5. Take precautions to avoid being a target of crime
--> Just act and dress regularly. Don't be a spot in a crowdness.
6. Contact your country embassy in that country in an emergency
--> Before you go, make sure that your country has a relationship with the nation you will visit. You don't want to go to uncertain places, bealieve me.