Working in Korea is a lot of fun! Aside from the outstanding culture and the beautiful scenery, the people are really great... and by people I mean the students... the adorable students that steal your heart and candy. Most hagwons (private academies), will have a general curriculum for you to follow. And if you're lucky, like I was, you'll get a lot of recycled lessons plans that you can use again! Most schools will let you be creative if that's what you want. Some schools will already have lesson plans for you. Others may have nothing, give you a pencil and point to the drawing board!
I work at a Poly school, which is a really big and prevalent chain throughout Korea. They have a lot of pre-made lesson plans for the classes, however there is a lot, and i repeat, A LOT of room for wigglin'. I got really lucky my first year with an a really flexible staff. They let me have creative control with my lesson plans. I was able to do art with my students, learn through a lot of games and experiments.! I for one would die of boredom if I didn't change the pass from time to time! If that's not your style, there are a lot of resources online that can help with lesson planning.