One should distinguish between active and passive vocabulary. Passive vocabulary is all the words you understand. Active — everything you use in everyday speech. Should pay attention primarily to the expansion of the active vocabulary.
Read the small text, and then summarize (or better rewrite) it from memory. Compare the vocabulary of the source text and your paraphrase. Check to see which words you missed. If they value you already know — so they are part of your passive vocabulary. If not — they can be learned.
To learn words on the list is unproductive. What you have remembered thus, kept in memory for long, besides work goes into conversational stock.
The main means of expanding the active vocabulary is to read a lot. Choose books that use a lot of unusual vocabulary, but at the same time try to keep the language the selected works were not overly complex or archaic.

When reading aloud, pronounce certain phrases and turns. Try to say the most interesting and captivating episodes. Especially useful to repeat the remarks and dialogues of the characters.
Pay attention to Proverbs and sayings. Make a note of those that meet new or unusual words. Compare these Proverbs with the situations of your life. Think of how you could apply them in particular cases, and, if given the opportunity to use a new expression, use it.
If you are learning a foreign language, watch movies without translation, but with subtitles in the original language. Repeat the dialogue of the characters, trying to capture the tone and context of what was said.
You always remember a lot more words than they use in speech. So, you need not only to learn new vocabulary, but also to activate already learned.
Take any small text and try as much as possible of the words in it to replace synonyms so that the meaning will not be harmed. Write as many options as possible.

You can also replace words with antonyms (words opposite in meaning), but avoiding the simple use of particle "not".
Selecting a few dozen words that you don't normally use in speech, make a cohesive text, which will include them all. Try to visualize that you just composed for the event.
Take any book. Select the word that you know but don't use in speech. Flip through the book from beginning to end and find all the phrases which use this word. Repeat each sentence out loud.