Woman Trekking. Trekking alone is not recommended. Even in the cities, walking out alone at night can be dangerous. Do not stay in bars and pubs till late night. Do not respond to the jerks who advances for introduction and friendship in such bars.
Follow the women-and-children rule. If you see women around, especially women with children, you've got less to worry about. This is critical at night. If all you see is men, men, men, high-heel it out of there.
Don't speak the language to creeps. If you're dealing with an unsavory guy who speaks English, don't say hello back. Shake your head or shrug your shoulders and say "No English." If he says "Speak Italian?" say "French, no." If he says "Speak French?" say "German, yes."
However, do learn such key phrases as help and get lost in the language of the country you're visiting.
Never look at maps in public. Memorize them in advance, or look at them in a café or your hotel room. In many cities you can buy credit card-size street and transportation maps -- which you can glance at inside your purse, so no one knows what you're doing. Sometimes I sketch a rough map of major streets and write down the exact addresses and directions for places I'm going, to avoid the map problem altogether. You might also want to bring a compass to help you get your bearings when you're lost, or just for navigating labyrinthine streets.
Carry embassy contact info. If you're going to a far-flung or potentially dangerous destination, always have with you a list of local embassies, with their phone numbers and dialing codes. Let the local embassy know you're there, and leave a list of its numbers with friends or family at home.
Check in with the folks at home. Tell friends when they can expect your calls and give them your embassy contacts in case you disappear. Also leave them phone numbers and addresses of hotels you may be staying at, along with a rough itinerary.
Always carry I.D. Keep your passport with you at all times. You do not have to store it with the hotel owners, no matter what they say. Many places are required to take down foreigner's passport numbers, but don't actually need the passport. Make photocopies of your passport in advance, and hand over one of those.
Don't wear a money belt. Once you fish for your bills, everyone will know you're a tourist. And once you're pegged as a paranoid tourist, you're a sitting duck. And don't wear a fanny pack. Only tourists wear fanny packs (and someone can grab your arms while his accomplice rips off your pack). Your best bet is to stash money in your front pocket or shoes, and carry whatever you carry at home -- just make sure it has a zipper.
Wear sunglasses to avoid scrutiny. People look away when they can't make eye contact.
Walk like you know where you're going. Studies show that if you exude confidence and strength, people are less likely to try to take advantage of you.
Be cautious in remote places. Some destinations contain open roads and beautiful scenery but few well-traveled places to stop and enjoy the view. You'll tempted to stop and look while driving, which is dangerous. Always lock your doors, even in small towns where nothing seems likely to go wrong. And never leave stuff in plain sight in the back seat.