Reddit reviews How to Teach English Book and DVD Pack

Those Groupon TEFL certificates (or any online cert, really) are the TEFL equivalent of for-profit American scam universities. Lower-tier employers would hire you with or without the certificate. Employers with actual hiring standards would either give it no consideration or immediately slide your resume in the trash can.

You might learn something about teaching from the course, but this book (which is used as the textbook for CELTA) would teach you more for less.

Check out /r/tefl.

A 40-hour course is pretty worthless. In my experience, any job that requires a TEFL certificate (or gives you a pay bump for having one) wants at least 100 hours, and increasingly they also want in-class experience.

I'd go like this:

• Will you teach for one year or less?
  
• Are you teaching somewhere where it's not required at all?
  
  It's optional. Do 40 hours if you want or read a book on teaching (This guy is well-regarded.)
  
  
• Teaching somewhere where they want you to have a TEFL cert (as a job requirement or for more pay)?
  
  Get at least 100 hours, preferably with at least a 20-hour practicum.
  
  
• Do you want to do this for more than a couple of years?
  
  Get a CELTA.

I also flipped through The Practice of English Language Teaching but I didn't read it in depth so I can't quite say. Amazon apparently has a table of contents in the preview section for How to Teach English so you could take a look at that to see if it's a retread or not.

If you just have Korean students speaking English with other Korean students, they'll be practicing what they already know, but not learning anything new. Students need instruction and guided practice before moving on to free practice. If you need help with lesson planning, Jeremy Harmer's How to Teach English is a pretty good primer in ELT.