How much time do you have?
No, seriously. The key isn't to be able to recognize every word they show you so much as easily figure out what the word means. The easiest (and most time consuming) way to do this is to study Latin, and maybe some Greek.
Second easiest, I'd recommend learning prefixes/suffixes real well, and getting good at process of elimination for strategies on what the different relationships, etc. mean.
Third, I'd say read lots. And not novels, but some good non-fiction type stuff, preferably humanities - oriented or not as academic. Perhaps even those 'SAT study' novels with different words picked out and defined (have not tried them, just saw them the other day in the bookstore and thought it seemed like a neat idea).
If your crunched for time, then flashcards would help...but be sure to not try and memorize different words so much as see how words relate to each other, how roots look different in different forms, and how prefixes can alter the meaning (not always the same in English!).