Firstly you need to understand that IELTS is a language based test that focuses to test your ability to comprehend speak and write English. For that, you just need to have a basic understanding of the language. In the Listening section, they expose you to different accents. Hence, if you are not exposed much to English of different accents, I would recommend you to watch as many English movies, web series you can. By this way, you can tune yourself to different accents as well as you will be entertained. Also, you should try one or two model listening tests of an hour each. You can get ample such stuff over the internet especially youtube. During practice as well as in exam please try to keep your concentration level high because your attention does count. Try to score more marks in the first 20 questions because they will be easy to listen and comprehend.