If it's available, listen to spoken English radio stations (many available on the internet), watch English TV and films. If you have a DVD on which you can change the spoken language, watch it first in your own language so that you understand the lines and the plot, then change the language to English and watch it again.
Don't worry about understanding every word when you listen, to begin with. You will find that if, for example, you have English radio playing in the background when you're at home, after several hours your ear will become accustomed to the language and you will understand more and more.
I can also recommend the TED website (www.ted.com) - you can find a lot of videos on the site (usually presentations). Find a few short ones, listen to them a couple of times, then switch on the written transcript that can be found to the right of the video screen so that you can read the text along with the sound, and see how much of it you understood.