Vocabulary is one of the pillars of language learning and especially significant for advanced learners. If you are familiar with the basic structures of your target language, you'll probably want to start saying and understanding more words!
My students usually ask me: «I'd like to get some system for vocab learning. Have you got any recommendation?» This question sure makes a good article. So here is one of my top techniques for learning vocabulary:
Research shows that building links between data helps us remember things and the way to make sense of that is to put the vocab into use. A classic memory technique would be to connect every word with a strong image (imagine a grumpy usher huffing and telling you where to seat). Then you can come up with a story that includes all your vocabulary — new and old.
I also like to to work with vocabulary sets, for example you can focus on cookery for some time. That way, the most common words will reoccur and you learn not only the word, but how to use it.
Remember, immersion is really important to make sure you produce language in context. Update your VK in the target language. Use it (new word) 5 times in a conversation. Whatever it takes, just make sure you have satisfied both repetition and context.