"What about your vocabulary, do you memorise definitions contantly or is it more about understanding?"
If I see a word I don't know [and am not too lazy] I look it up, try to remember the context and try and think about how/where else it could be used. I sometimes do it the other way round: when I'm thinking of something like an emotion, or concept I can't name, I try and see if a word exists for it [this is harder, though.] Sometimes it's helpful to check out the definitive meaning of a word, even if you are perfectly comfortable with using the word, just to be sure.
Of course, as they say for learning generally, with some words, learning them is a lifelong process. You could say that studying some Arts subjects is merely about furthering your understanding of certain words.
Disclaimer: I did EL, and wasn't even close to gunning it but I like words