I am not an expert but have some language exchange experience in the US for a year.
Most Koreans tried to learn English but didn't really try to teach even speak Korean to Americans so I started to teach them because it's fair. I thought them 2 or 3 of useful expressions and grammar points every week and answer them as well when they have questions with Korean that they've got from Korean language school.
I was surprised that there are many materials to study Korean with in the school. It was well organized and divided based on learner's level. But sometimes they brought ridiculous materials such as a really old literature, which they would do acting with. They asked me to help with it but I didn't even understand some words. I guess the school's intention was making the class various to make students having fun. But in my view, it is just waste of time. Not only can it waste their time, but also can give them misconception with what they should do to reach their wished Korean level.
In a nutshell, don't try to learn everything perfect in the school. Focus on basic stuffs on books first and don't obessed with all things around the school.
More tips will be continued.
p.s. I know I've made many mistakes in writing this in English. Pls correct me if you like.