I'd listen to various English TV Series and songs (be it American or British). Within Britian for an example there's a slight difference (or most of there time there can be) when it comes to us Scottish speakers since we sometimes throw in some Scottish meaning and words that aren't likely to be heard from the England side of English. We also have our own dialects that can take a while to get used to. Same might go for Irish and Welsh that speak English, but usually I can understand them fine anyway. ^^
Thanks a lot
It’s best to start with English TV series.
Download any TV series with English subtitles and watched it twice or thrice. Listen to the sound and at the same time look at the subtitles to verify that you heard it right. I watched Gilmore Girl series myself and it really helped me to improve my listening skill.
Further you can listen to the BBC News. They speak well and are easy to understand.