How do you learn vocabulary?

Over the last few years, I've been exploring different methods of learning vocabulary. I've played with Spaced Repetition systems like Anki or The Lietner System, I've also tried using a memory palace! (That worked really well for Japanese Characters!). 

I think there are lots of different ways to learn vocabulary well. There isn't one best way. We all learn differently.

I have found that there are three principles that help a lot to learn new vocabulary.

1. It has to be interesting/fun

If you don't find what you are doing interesting or important, your brain probably won't try to learn or remember what you are doing!

2. Try focusing on learning passive vocabulary

Memorising new words isn't natural, that's why we keep forgetting them (but maybe it's only me who always forgets them)! Because of this, I try to focus on learning to recognise words, rather than to memorise them. This approach is also how we learn words as babies.

3. Context, context, context

Learning a word in context is probably the most important principle. Learning a word in context connects it to other words/ideas in a sentence. So we have more connections to it in our brains!

What do you think? Is there a fourth principle? How do you learn vocabulary?