When teaching ESOL to elementary sudents, what are the first/basic things to teach and consider?

I want to learn to teach ESOL in another country (considering South Korea), but I have no formal training in this subject. I have taught other subjects though. I was wondering what should be the first things a teacher should cover for classes in grade levels 3–6. I feel that once I know how to start off, I should be able to get rolling on my own. Thanks in advance!