Taking a taxi in a foreign country can be a frustrating experience. It is best to do a bit of research about taxi protocol where you are going because calling one and hailing one can be quite different then what you would normally expect. In particular it is quite important to know how a cab driver expects to be treated because this can help save you a lot of money. A disgruntled taxi driver can screw you up in all kinds of ways, including dropping you off at the wrong destination or driving away with your luggage.
It is also a good idea to hail a taxi yourself if possible. Do not let a doorman or someone else do it for you. Never get into a cab that you suspect might be driven by someone inebriated, unreliable or suspicious. You can often determine this by looking at how well the vehicle has been cared for or by how well the driver is groomed. An unclean or rickety vehicle may belong to someone who is less responsible or ethical.
Another thing to consider is whether or not the address you have in your hand or that you have been told is in the local language. This is a good idea because it is so easy to mispronounce words in the local language or have a driver misunderstand where you are going.
If you are taking a taxi with a meter make sure that is set to zero when you get in. If you negotiated a flat fee to get where you are going then be sure that the amount is confirmed before the driver sets you both off a journey.
If you call a taxi at night make sure that it arrives in a very well lit place or in a place frequented by a lot of people. Preferably you are ordering a taxi from within a hotel where the concierge inspects all who drive up.
It is also a good idea to keep a watchful eye on your bags while you are loading and unloading the luggage. Do not let your luggage sit on the sidewalk unattended or you could be the victim of a crafty passerby.
If traveling in a foreign country it can be a good idea to get good advice beforehand about which are the best taxi companies to use and what types of local transportation leave you vulnerable to getting lost or being attacked. In some countries it is more advisable to take public transportation than a cab.