I don't advocate memorising vocabularies in the dictionaries robotically. Read more English newspaper. For me, I read several pieces of news everyday(6-7 in average). I'm a Hong Konger so I read SCMP, which is local. I also read the Guardian(from the UK) just to get some international news. You can distinguish which are the commonly used words, so you can check them up in the dictionaries and memorise them. It's more effective than reciting vocabularies blindly.
I've read English newspaper incessantly for 3 months, and i see my English improved
Raise your words, not your voice. It is rain that grows flowers, not thunder.
In my opinion,if you have to improve your English in a short term just to get good grades in an imperative entrance exam,I consider the method that I render on the third floor indispensable.