Ask the director for the emails and phones of old and new esl-teachers. you can also post a paid ad in the local english newspaper and ask former eslteachers to contact you.
ask to see pictures of the apt or visit the place before you sign the contract. how many students the school have. are you going to a classroom with a group of students already there or the classroom will be empty and they will use you as a poster white face to try to attract new students, in the meantime you don't get paid in a classroom without students. it happen sometimes to some of those teachers who accept "good" salaries and conditions in small schools and traveling from abroad.

Good luck! (haeng un eul bil eo yo)