These language schools are often taught by Filipinos who can speak English and by "backpackers" By backpackers I am talking about young adults who want to study and learn by travelling around the world and usually run out of money sooner or later. Often they stumble into one of these language schools, teach for a few months to make money and then quit and resume their journey of discover.
Some of these backpackers actually fall in love with teaching and simply stay on or come home to North America or Europe and study teaching formally before they try to get a job in their own country and begin teaching as a career.
Conversely, many discover that they hate it, which is also good, because then they can eliminate one thing from their potential list of careers when they are ready to work full time. But, by going to teach at a language school, they can teach "light." Try it out with very little risk and lots of potential gain. They may even find their passion in life, both metaphorically and literally.
You do not have to take a a Toefl course to get a job teaching. When you start to search for jobs you will see all kinds of come on ads trying to engage you in spending money to take a course with a guaranteed job at the end. If you want, spend your money but if you are just wanting to get a taste of teaching, don't bother. You will learn on the job. Just show up and prove that you are a native English speaker, can walk and chew gum at the same time, and are willing to learn. They will ask you to demonstrate a sample lesson and if you seem to be able to control the class you will be hired immediately. Don't worry about not knowing what to do....either do the other teachers.
It is in this kind of situation where you will learn about yourself and if you are cut out to be a teacher. Try it, you might like it. If you like, write me and ask me which countries are better to teach in and which websites you might find helpful. Good luck.