Immerse yourself in English as much as possible
Immerse means to be surrounded by something. If you are immersed in English, it is all around you. Of course this isn't always possible, but you can do some things to surround yourself in English from time to time.
listen to the radio in English. If there are no English radio stations where you live, listen to one on the internet.
Watch TV and movies in English. If you have English channels on your TV, watch them. If they have subtitles (the words written in your language) underneath the picture, see if they can be turned off. Some people even tape paper across the bottom of the screen so they can't see the words. Most DVD's are great because you can choose the language you want to hear.