Learn the Vocabulary
It may seem obvious, but learning vocabulary is very important. Words that we don’t know do not sound like words; they sound like noise. Of course, you can learn a new word by hearing it, if it is the only one that is new for you. But you still probably need to hear it several times.
You can study vocabulary for some situations, like listening to a speech, if you know the topic before you listen. For everyday conversation, usually there is no special vocabulary to learn. In that case, find the list of the most common words in english and learn the first 200 perfectly. That should make things a LOT easier.
Choose each word, one at a time, and try to listen FOR it while you watch a movie. Get used to hearing it. When you are satisfied, do it again with the next word on the list.
Here is a tag to the list:
Good luck, and happy listening!