There is way too much to write on this topic, if I try to form it all into paragraphs. Allow me to break it down, bullet point style. If all of these rules can be applied to your future travels, that's neat. If not, be sure to apply every one that relates.
When traveling abroad, everyone should do these every time.
-- Plan Ahead: Plan for security as hard as you plan for fun or business. Research, connect, and pack for circumstances that are likely to go wrong. In a crisis situation, you don’t have time to plan. You can execute what you have planned, but if you don’t plan ahead, you won’t know what to do.
-- Maintain a Low Profile: Don't draw attention to yourself. Learn local customs so that you can blend in. Act like you have been there before. Act like you belong.
-- Plan Hotels/Lodging and Ground Transport in Advance: Be sure to always have your itinerary and contact cheat sheet (cheat sheet below) whenever you leave where you are staying.
-- Stay Aware and Vigilant: Things that seem out of place look and feel the same, regardless of what country you are in. You should know what fits and doesn't fit.
-- Check the State Dept Website: The U.S. Department of State has a page for every country in the world, where it lists all known difficulties and current threats to the safety of visitors. Keep in mind, it’s the State Department’s job to warn you about everything that could go wrong, which can be different to what is likely to go wrong.
-- Register with Your Embassy: The Smart Traveler Enrollment Program, from the State Department, makes a destination’s local embassy aware of your arrival and allows them to keep you updated with the latest safety information. If an emergency happens, like a natural disaster or terrorist attack, the local embassy can get a hold of you quickly to share important information or help with evacuation.
-- Make a Cheat Sheet: On a note card, write all emergency contact info, non-emergency contact info, addresses (hotels, embassy, etc.), and an itinerary. Laminate the card. Make sure that at least 2 others have the info (text or email them a picture of the card).
-- Ask the locals: Most front desk hotel workers will steer you away from dangerous areas, but always get a second and third opinion. Don't trust cab drivers. It is safe to assume that they are going to set you up.
-- Lock up your valuables: You will never need your passport, so leave it in your hotel safe. This goes for anything else of value. Computers, tablets, camera gear, phones, jewelry, and cash are all big flashing criminal beacons.
--Acquire a Weapon as soon as Possible: Odds are, you didn't travel across a border with your pistol. Get your hands on a knife, letter opener, etc. as early as you can. A steak knife from dinner will work just fine.
-- Buy a hard rubber door stop and use it
-- Copy your hotel emergency exit plan, and keep it on you.
-- Stash hidden cash in 2 different places on your person.
-- Don't give too much info to locals. OPSEC!!
-- Tether your bag to your belt with a carabiner.
-- Nothing in your back pockets, ever.
-- Dress for the situation. Dress differently in Mexico and Syria.
-- Project situational awareness. Be a hard target.
-- Back to the wall if reading or using a phone.
-- Tell your bank where and when you are going.
-- Eat at popular restaurants with long lines.
-- Inspect ATMs before using (skimmer, camera, etc.)
-- Don't get drunk.
-- Avoid large gathering/tourist sights. This is where trouble lives.
-- If you are caught in a mob, blend in while looking for your exit.
-- Trust your gut!
-- Pack a hat, and put long hair up under it.
-- Never be alone, ever.
-- Carry a whistle.
-- Never be alone, ever.