What is the must-do thing in the first month after arriving in Korea?

There are five things. (1) Those staying for more than 90 days must register as foreigners within 90 days from the date of entry (Immigration Control Act Article 31). (2) Create a bank account in your name. If you receive it in your own account, there will be a deposit record; if you received it in cash, keep your payment details and pay stub. (3) Check whether you are enrolled in health insurance through your company. (4) Photos of the employment contract and pay slip are kept each time you receive them. (5) Enter important dates in the app's deadline calculator, log in, and schedule reminders. If you want to receive it on your phone, turn on push notifications. For work conditions, ask 1350; for residence or visa, ask 1345. 1350 offers consultations in English and Chinese, and you must pay the phone bill. 1345 consults in multiple languages.