The goal behind my "word of the day" posts was to learn words, but I realized it's as useless as Duolingo. The only way to learn a language is to expose yourself to it.
Just as you can't learn German without speaking it, you can't improve your vocabulary if you stop reading it. I have already forgotten what 'tact' or 'alacrity' means, even though I have written about them.
I've also found that it's as useless as taking notes in class. It is about practising your understanding, not just writing it down. There's no point in learning a language if we're not going to use it.
Now that I think about it, that goes for everything.