1. Get your Alien Card early. You should ask your co-teacher to bring you to immigration on your first or second day in your city. The earlier you get this card, the easier life will be. You can’t open a bank account or get a cell phone without this card.
2. Ask if any of your teachers has a spare cell phone. These days, people change cell phones like they do socks. Chances are someone in your school has an extra phone lying around. If they let you borrow it, you can then take it to a cell phone store to get a pre-paid plan, which is the most economical (unless you want a smart phone or use your phone incessantly). I got my plan through a place called NRC in Daegu. They have an office near Banwaldong. Super cheap.
3. Set up a KEB (NOT KB!) bank account. This is the best bank account for a waygookin: cheap fees for sending money back home; online banking that also allows you to transfer money overseas, which no other bank has; mostly English-speaking staff; and a check card that you can use overseas when you have your vacation in Thailand or China.
4. Check your ondol. When your teacher first shows your apartment, make sure you ask about the ondol (heater). Find out what buttons control the water heater and what buttons control the floor heater. Find out how to turn it off correctly and set the temperature correctly. Too many friends of mine didn’t figure these things out early and had very large gas bills.
5. Treat your teachers to pizza or chicken on your first payday. Not only is this polite, but trust me, if you do this one kindness, it will be repaid 10-fold throughout the year and you will always have food on your desk.