I find that vocabulary is somewhat difficult to learn through osmosis. For me, it's best to study vocabulary separately and then when you encounter those words you've studied out in the wild (talking to native speakers, listening to JapanesePod101, reading books or Manga, &c.) you'll have 「なるほど!」(Aha!) moments when it clicks and you'll forever remember those words.
I've used Anki and other flashcard software before, however, I always found that it was tedious and time consuming to make my own decks while using pre-made decks never really took into account what I might already know. I never found anything that worked for me so after a long time searching I, along with a friend and fellow Japanese studier, set out to make my own tool.
We ended up making an iPhone app called Goi (
http://www.goiapp.com) that's made with the sole purpose of building your Japanese vocabulary effectively so you can start understanding and enjoying native materials as quickly as possible. It uses your existing knowledge to help you learn new things. Each person will be taken on their own unique path to learning vocabulary.
Vocabulary is just one piece of the puzzle though, albeit a large one. You'll want to expose yourself to as much native material as possible and in the end find what works for you best.
Disclaimer: I made the app to which I refer above. If this violates any forum rules please feel free to contact me and remove this post
![Smile :)](/static/images/forum_ro/smilies/icon_smile.gif)