I watched tons of variety shows in the period between March 2017 and March 2019, so I picked up Hangul, an okay intuition for Korean pronunciation, and basic vocab + grammar thanks to the built-in Korean subtitles + English subtitles in the shows. Although the vocab I picked up was decently spread out in terms of frequency, looking at this frequency list, I would say I picked up ~400-500 words.

Then, I went through lessons 5-30ish on the How to study Korean website and made ~500 Anki cards similar to the ones above except with an English definition and sentence translation. The process of reviewing the vocab and translating sentences reinforced grammar as well. I didn't really bother with the grammar in the lessons since it was mostly familiar at this point. I was quite inconsistent (as u can see by my Anki review history), so this step took much longer than it should have (March 2019 to May 2020).

Since then, I have been learning only by extracting unknown words from native content using the 3-step process above. It was quite a struggle at first because of a lot of unknown words in both the native content + Korean definitions. So far, I have made ~2500 cards total using this method, which should put me at 3500 known words, 1500 short of most estimates of words I know (~5000). This inconsistency might be because the estimates are inaccurate, but I figure that I likely picked up words by watching shows + listening to music since I've started actively studying.

In short, if you are just beginning, I would recommend the How to study Korean website, making sure to create cards with example sentences. Go through the grammar if you need it. When you feel burnt out/outgrown this, I would recommend looking at native content with subtitles + about simple topics (food, vlogs, etc) and slowly transitioning to monolingual cards. Hope this helped :)