Where can I teach?

The short answer is: You can teach anywhere where English isn't an official language, but it'll be harder some places than others (I even got into a teaching program and got a job in public school in the USA).

The looooong answer is:

First off, your nationality matters. For instance, in Europe, Brits are Kings, whereas in Asia the USA reigns supreme. Canadians tend to fall similarly to the USA, while South Africa and Australia tend to be lower down the line no matter where they go. That said, nowhere is off limits for anyone.

You may hear people say that Western Europe is a no go for non-EU citizens and for the most part they are right. If you are, for instance, an American wanting to teach in Italy, no one is going to reach out and hand you a job and visa. On the other hand, if you are willing and able to go there and pound the pavement from school to school and search out one-on-one private lessons, you can make a niche for yourself and I have known many people who have done just that.

This is about as hard as it gets and with a little cash reserves and perseverance, add a bit of experience in Central or Eastern Europe for good measure, you'll be fine if not legal. I wouldn't necessarily advise anyone to live 'illegally' anywhere, but it is a rather common practice nonetheless. If you aren't concerned with making a long term life and don't make trouble with the police the fact of the matter is you aren't going to be thrown out of the country. Even in these times of tightening visa restrictions in areas many, many people live under the radar for a year or two abroad in Europe. Before you throw caution to the wind though remember that it could cause you stress and make it harder to find work.

Largely though, you are able to work anywhere without much difficulty. The most popular or frequented places to teach are Prague, a TEFL Mecca, and S. Korea, a place to actually live abroad and make a lot of money. In my time with TEFL I have known people to teach in S. America, all over Europe, Asia and Africa. The key is to find the place that fits what you are looking for.

Feel free to ask about any country and nationality combination and I'd be glad to write something up. I may also be able to put you in contact with someone who has worked there or is still working there.