Cambridge Communication (CCL Aviation) has a good reputation, and has been advertising in Flight magazine for Korean Air recruitment.
It's probably best to have well over the minimum required command experience, and hours on type. The SOPs are excellent, and most of the co-pilots try hard to help, but you are very much on your own because of language and cultural difficulties. The more previous experience you bring to the job the more you are likely to enjoy it and cope with its unique challenges.
Contact CCL by emailing the principal, John Hitch, at:
[email protected]
or look through back numbers of Flight. They were advertising there a few months ago.
Good luck