If you decide to teach EFL - do what honorable people do - get yourself trained in how to do it properly.  People in this part of the world pay, what for them is a significant amount of money, for their ongoing education in English.  Please do them the service of educating yourself in how to do it well.  Getting yourself trained will also greatly increase your job satisfaction - when you KNOW you are doing a good job, and you can see your students progress.

Look for a school that offers you the "internationally accepted standards" of at least 100+ hours of classroom instruction - and a minimum of six hours of observed teaching practice.  That level of training will assure you of the basic skills you need in the classroom - and of a certificate that will be accepted internationally.  Study at home and distance courses will not generally be accepted as meeting that standard.

On another page here are comments written on different forums and via e-mail  that people interested in Teaching English Abroad might be interested in.  It is by no means exhaustive or complete - but it might give those considering this career option some food for thought.  The EFL FAQ

If you are unsure how to pick a TEFL school and of all the things that should be considered, check out this guide:
How to Pick a TEFL School

Would you like an opinion on which TEFL Certification Course offers you the greatest benefit?
Phuket Delight's Recommendation

TEFL eBooks might have just what you need to know . . .

Resources for EFL ESL Students