There are a few things you should know first.
A TEFL certification is the first step to becoming an English teacher. There is some debate as to whether or not you really need this certification. The truth is here in Argentina, you can probably find a job without it, but with the certification you will find a better job, and be far more prepared to teach.
I went through a company called LanguageCorps. http://www.languagecorps.com/
Based in Colorado, LanguageCorps offers TEFL certification courses in multiple locations, both domestic and abroad. They offer pre-departure support and job placement assistance. They serve as an intermediary support, providing peace of mind that you aren’t totally alone in a foreign country.
During the course LanguageCorps can arrange living accommodations should you desire with a shared apartment or home-stay. I chose to live in a shared apartment, and they set me up in a large apartment shared with a young argentine photographer and another boarder.
The TEFL (teach English as a foreign language) course itself is a month long and very intensive. Time is divided between studying English meta-language and grammar, learning teaching techniques and practice teaching classes of real Argentine students of various levels. Class is about 6 hours a day, with a lot of homework and lesson planning. The work environment is serious, but the other participants are fun people who want to enjoy the experience. You are instructed by a TEFL trainer along with a teaching assistant who critiques your practice teaching lessons.
After the course they give you some local business contacts to apply for teaching positions. If you contact them, you will most likely be offered an interview, and if that goes well, a job. LanguageCorps doesn’t provide a job for you, but they help make the process easier. It is intimidating to job hunt in a foreign culture, so they help you write a proper CV and have practice interviews. The course really prepares you for teaching English, and working as an English teacher here in Buenos Aires.
I was in a class of 12 students. Most were serious about teaching, and a few were just looking for an excuse to spend a month abroad. After six months, half of the class has already gone home, unable to really make it as a teacher. The other six of us are here working and thriving. Should you wish to teach English in a different city than the one you studied, LanguageCorps still offers their support.
Language schools and institutes look for candidates with the TEFL certification, and they also value teaching experience. Taking a TEFL class can gives you both.