In fact, when a listening comprehension exam is being taken,what counts as another core element besides the English ability is the psycho-status of the test takers.
To improve your listening ability, practice makes perfect is the only way out. There’s no shortcut. I believe shortcuts are for those talented people, not for the frustrated common brains. Just do it. But please be sure to set your hands over other aspect of English as you plough about the listening part, since English is a language, in which a manifold of skills add fuels to one another. This is a better way to have a profound English base:
1. Writing in preparations for talking.
2. Talking (imitation the standard).
3. Get used to the sound and you naturally and unawarely improves your listening ability.
4. Join interactive English programs to make the language real.

Juse be patient enough to get your goal step by step by step. However, there are some other ways provided by training schools, eg. the New Oriental TOEFLE and GRE training. In most of the cases, you are trained to have English as a test paper full of questions in the way abroad. But not as a language that is going to bring you joy in communications. (Well, I am not talking about those several exceptions.)

Rlex and have fun during the learing of English is a much healthier way.
Make full use of the abundant materials and shift between ways to learn (eg. reading today, watching TVB pearl tomorrow, go to English corner next week...and so on) and you never get bored by English as many others have complained it to be. In fact, it’s funny. :)