1 - Being illiterate is difficult.
We take for granted being able to read simple things like store fronts and street signs.
When you touch down in the Far East you will effectively be put back to square one in terms of communication. Not only will you have to communicate in a new language, but everything is written in 한글 (Hangul), Korea's script.
While it's know for being very easy to learn to read phonetically, building your vocabulary and reading it at a glance takes much, much longer.
Depending how you look at it, it can be very exciting or very overwhelming.
Korea sees many tourists though, and in places like Seoul and Busan most Hangul will be accompanied by English. The further you move away from big cities however, the less and less English you'll see (and hear).
2 - Salt and Vinegar chips are a no.
Of all the difficulties of living in South Korea, the most criminal is the inability to find Salt n Vinegar Pringles
For whatever reason salty never became a very popular taste In Korea.
Everything snack-related is sweet. Everything.
Savory foods do exist, as do western ones, but they're often sweetened to accommodate Korean pallets. This often leads to some pretty funny instances of missed-expectations when trying food you think will taste a certain way.
3 - Mundane things can now be a mission.
Imagine ordering a meal in a restaurant. The wait-staff don't really speak English and the menu is in not only a different language, but a different script. It's totally doable, it just takes a lot more thought and awkwardness.
Now imagine opening a bank account.
I'm not saying it's terrible: on the contrary, it pushes you to grow and is a great way to learn another language. It just means that going out to what you take for granted as simple-things like posting mail can take a bit more work and planning.
4 - Get your banking sorted.
Before you leave SA, notify your bank you will be travelling, otherwise they will block your bank cards as soon as you try to swipe abroad.
Even more importantly, get them to change how you receive your OTPs (one time passwords). Receiving them by SMS is not good if you don't have roaming or change to a Korean SIM card, so instead ask them to send them to you via email. This will allow you to make changes to your home bank account while abroad and send any money you have in it to whoever you need to.
5 - Winter is way harsher.
Now although I've waited my whole life to be able to tell people younger than me that I walked kilometers uphill through snow to get to school, It's not all great.
Snow is cool, walking to school in -10 °C isn't.
Korea winters can get very cold compared to South African ones, meaning that if you're not in a city with plenty of (warm) things to go out and do, you end up spending a lot of time in your apartment. This can lead to cabin-fever, homesickness and loneliness, so finding something to keep you busy and meeting with friends whenever possible is incredibly important.
6 - No need to bring Rooibos.
For whatever reason Rooibos tea is very common in South Korea, and said taste of home can be found in most coffee shops, so no need to fill bring your own when you fly over.
7 - Google and Apple maps? Find alternatives.
It sometimes feels like South Korea has a bit of a....blind spot in terms of accessibility for foreigners. One such example is their refusal to license up-to-date map data to western companies like Google or Apple. The official reason given for this is the fact that the country is still at war with everyone's favourite Dictator. The commonly accepted real reason however is that the South Korean government doesn't want foreign companies to disrupt local Korean companies like Naver and Kakao's monopoly on the market.
Google Maps still kind of works, it's just very inaccurate and doesn't give you walking routes. Good alternatives are the above mentioned Naver and Kakao maps along with city-mapper for something more English.
8 - Uber doesn't work.
Yup, everyone's favorite ride-sharing app is illegal In South Korea. So your super convenient (and cheap) get home from the club method is out the window. There is an alternative, Kakao taxi, but it simply hails you a regular taxi at regular taxi prices.
9 - The time zones are a bitch.
Unless your friends/family are self-employed or still studying, the 7-hour time difference between K-town and home can be super frustrating. Your 5pm is their 10am and their 5pm is your midnight, meaning disrupting weekend plans or groggy-eyed 5am calls are you only way to have good long catchups with the people you miss.
10 - It's easier than you're worried about.
Moving to a foreign country to teach can be daunting. Before you leave you will likely be worried about how difficult it will be and whether or not you will be able to effectively teach. Relax.
Just like any other job, it gets way easier the more time you spend doing it. A lesson that took you 2 hours to plan at first will soon take you around 30 minutes or less, and the nervousness you felt teaching your first class is eventually replaced with comfort. The first few weeks will be tricky, but just go with the flow and remember it gets better and you'll be fine.