Flash cards are very good for memorising and recollecting words and phrases when you use flash cards. (Sounds strange, but it is true). "Stimulus-reaction" this is how flash cards work.

I wish I had seen this question earlier! My opinion is that flashcards are hugely helpful for vocabulary learning. To me, building up your vocabulary is very much a memory game. In that respect, flashcards are a great way to push knowledge into your head. I would personally use a Spaced Repetition System (SRS) to help you learn. All that basically does is help you review the cards you don't know as well more often, and test less frequently the cards you already know. There are a lot of programs and websites that do this now. The one I use is called Anki (http://ankisrs.net/), and it is open source. Again, it all depends on what works for you. I hope that helps.

I've studied for being a teacher and, at university, they tell us about the benefits of using flash cards (overall with children). They train memory and make easier the bored work of learning just words. It also depends on how you use the flash cards and if they are good and well designed or not.

In my opinion, just choose a nice vocabulary book and then start to read regularly and repeatedly~~~