Be prepared for a few shocking adventures while searching for a good meal, from the viewpoint of a Westerner. You might not enjoy live octopus, especially while its suction cups latch onto the insides of your mouth. If you are famished, or you have had enough adventures for that day, go straight to the pizza restaurant or other fast-food establishments. Such places are growing like mushrooms nowadays. In many small places, however, you won't find anything other than local restaurants.
Korean food is very spicy.
Start by sampling food from stalls along the road. Otherwise, find a restaurant filled with Koreans. Spy on what they are eating. To order, point to a dish that looks attractive to you. To order from the menu, most often written in Hangul, on banners hanging from the walls, is gonna fail for sure, even if the waiter tries to help.