Having an extensive vocabulary is one of the most important parts of language learning, but I feel the greatest trouble we have is that we think in our native language when speaking in the new language. We try to translate all the time. If straying away from this concept you will remember the words much better.
In my previous post is discussed the way I think it is best to start learning a language. Combined with that technique here is what I suggest:
Get yourself a notebook in which you write all new words you come across, but note: DO NOT WRITE THE TRANSLATION IN YOUR NATIVE LANGUAGE. We are trying to stray away from our native language when speaking in another language. When learning nouns, remember to write the definite article from the Nominative Case in front of it.
Group the words into sections and divide the book as such.
Use colour codes for genders, cases or parts of speech. Whichever your heart desire.
Revise this list every night before bed by simply reading through it. If you do not have the time to go through all of it, go through a section or a single page. The key is just to revise the words you have learnt every day!
I would love to hear from you if you want specific posts and please, do tell me what methods of studying you use to learn languages.