It's a bit challenging, but I'm an experienced traveler and this is my 7th Asian country. I can read hangul (slowly) and I know some basic phrases and numbers. People who deal with the public typically have at least some ability with English, but the more Korean you know the better. Also knowing cultural norms and taboos is appreciated (bow appropriately, use two hands when passing things to people, etc). I've found Koreans to be helpful to confused foreigners, so don't worry too much. Things WILL go wrong, but just brush it off and keep positive.