Subways in Seoul are really easy to use if you know your station ahead of time.
In Seoul, temperatures vary greatly between summer and winter. The highest is 38°C (102°F) which occurs between July and August, while the lowest is about 10°C(14°F). If you plan to visit between June and September, it’s likely to be very rainy during this period.
ATMs in the subway stations might not display English on the screen so you must go to an ATM in a bank.
Tipping is considered degrading in restaurants, so a nice bow and thank you will do.