Internationally, TEFL is the most widely recognized qualification for teaching English abroad. Most schools will specifically ask for this certification and even when it's not listed in a job's minimum requirements, teachers are more likely to be hired if they have it. International employers take note of a TEFL certification and prefer candidates who are trained to teach English as a second language.
Even if a school hires you without a TEFL certification, we highly recommend enrolling in a program regardless. The coursework will offer invaluable insights into classroom management, games, and advice for foreign teachers.
Teaching abroad without the proper training can be daunting. Good TEFL courses are designed to assist you in the classroom. Remember, your students will have a low-level of English and succeeding in the classroom will take more than just speaking English.