Most people are visual learners. So by printing out or drawing an image related to the word (on cue cards maybe?), you can remember the word. Also, make sure to not blindly memorize the vocab because you will definitely forget it in the future. Understand what the word means, relate it to an image, idea or situation and the word will spring back up to your mind whenever you think about that image, etc. Good luck :)
Easiest way? Read. A lot. And when you come to a word you want to add to your vocabulary write it down IN CONTEXT. Then revise.
By using it in context it will help you to recall the meaning when you see it somewhere else.
That's the method I used and my vocab is quite good. These days, with eReaders and computers you don't even need to go looking for a dictionary.
Read a lot of books and novels.