I believe the key is to recognize the vocabulary in context regularly. That is to say, read, listen, speak, or write regularly enough so you keep encountering the same words again before long.
I don't believe in any of the gimmicky methods that work with an artificially created word list. My gut feeling is that they distract more than help in most cases, giving one a false sense of having achieved something.
The essence of language learning is in getting familiar with the vocab and structure of its sentences. The key is to steep your brain with as many impressions of meaningful, actual usages of them as possible, always in context. Simplistic terms like "cat", "dog", "house", etc. are the easiest part of learning and they will come to you over time one way or another. The more difficult and crucial to learning is the diverse ways of how the stem words are used (get, take, make, and how they combine with other to create new meanings), and how abstract things are represented in the language - these cannot be easily learned using a word list or flashcards. Simply put, context is everything about a language.
So unfortunately, there is really no short cut or an easy way.
My advice is not to fret about memorizing isolated words too much and just to keep reading and listening to good texts concentrating on the ideas presented. Do it with a longer perspective, thinking in years, and you'll get there one day.
Here is a way to learn 700 words per week!
1) Pick 100 words randomly from a dictionary of your target language
2) Bake 100 cookies and engrave one word onto one cookie. Do this for all cookies.
3) Pick up 1 cookie at a time, read out the word on it, then eat it
4) Eat all 100 cookies
5) Do it everyday
I believe by eating the word literally, you are going to memorize it forever.
As you can see, the set-up time is huge, but that's irrelevant. It is only a one-time thing (per day). The actual time you spend is when you are eating the cookies. If you eat 5 cookies per minute, it will only take you 20 minutes each day.
When I learn a new word I like to create a vivid mental image to associate it with. For example, the Persian word for "comfortable" is "râhat", it sounds a bit like "row hat" in English. So I pictured an enormous upside-down hat floating in the river, and a man sitting inside the hat on a very comfortable padded chair, rowing the hat down the river. A word is just a mix of random sounds, not easy to remember, but a strong association is impossible to forget!
It takes 2 minutes to think of a good mental image, but saves time in the long-run, especially for words you constantly forget!
It's important to note that the image must be associated to the <em>pronunciation</em> AND to the <em>meaning</em>. If I pictured a man sitting comfortably in a boat, the pronunciation association would not be there. If the man was standing in the hat (instead of sitting in a comfortable chair), the meaning association would be lost.
Of course, lots of repetition, lots of use (and lots of cookies!) are essential as well.
