So there is a lot to do before you book a flight. First of all you have to check the date of expiry of your passport. If it is going to expire soon, extend it (could take up to 8 weeks). Check whether you need a visa or not. You can look up the requirements at the government’s (embassy) website. Keep in mind that it is going to take some time to apply for a visa, depends on which country you want to visit.
So for me as a german citizen with a german passport, there is no need for a visa to travel to South Korea (Seoul). LUCKILY 🙂
Source of the german passport picture I’m using here: