When Dr. Peterson mentioned his experience with Korean began in 1965 and that there weren't any Korean language textbooks then to speak of, so he had to use older phrase books to begin to learn the language. This reminded me of the old Myongdo's textbooks for English learners which were missionary related as well. I went back to check the publication date, and sure enough it wasn't until 1968.
I was using these Myongdo"s Korean 1 and 2 when I arrived in South Korea in 1987. My sister in law who is a native speaker and had the good fortune to become an Asian studies assistant professor, joked to me, one time about how "poor" those textbooks were once, laughing at the dumb drills. I had to laugh too because it was all I had for years- I had great difficulty remembering the grammar lessons, and I admit, the drills were tiresome and I couldn't remember them. This in spite of the fact, I looked at them so many times, the bindings fell apart.
I think memorizing lyrics from South Korean popular songs, watching Kdramas, then translating song lyrics and short news reports, moved me along. The biggest breakthrough was going through the free "talk to me in Korean" TTMIK lessons several years ago.
It's on again off again with the Hanja. The best advice I got on this was don't spend too much time on it. Spending too much time memorizing the characters will detract from concentrating on ordinary hangul reading and listening skills.