To teach English in Korea you'll need first and foremost to be a native English speaker and have a university degree. Granted you have those qualifications you'll need then to prepare some paperwork and documents. These documents can take quite a bit of time to process too.
What are the required documents?
- FBI apostilled criminal background check (CBC)
- Apostilled copy of your diploma
- Possibly university transcripts
The CBC must be done nationally. Previously a state level check was enough, however now you need a national check through the FBI and have it apostilled in your state.
Lastly individual schools can have their own requirements.