What is the best way to earn a useful ESL teaching certificate? I'd like to teach English abroad...?

...but there seem to be a plethora of online courses, on site courses, and lots of conflicting information. Some of these courses are very expensive. It seems the more I research, the less certain of the facts I become. I'd very much like to hear from people who have successfully done this- where did you study? What kind of certificate did you receive? Were you successful in finding work? I'd ideally like to work in Poland, Russian Federation, Slovakia, Bulgaria, Hungary, Estonia etc if possible. I'd like to hear your thoughts and experiences. Thanks.