The common belief among students getting ready for taking IELTS or TOEFL is to listen as much as possible, as often as possible from all potential sources, in all possible dialects of English.
This approach might efficient with advanced students. Some upper-intermediate students can follow this approach too.
What about those whose command of English is at a lower level? Well, I would advise them to refrain from listening to randomly selected materials, especially if they find them too difficult and as a result, discouraging. No one wants to get discouraged, do they? Instead they should choose carefully their listening practice by making sure it is at a suitable level. An ideal listening exercise should enable learners to guess the meaning of new words from the context. Besides, they should be able to follow the main idea of the recording without difficulty. To find out the level of your English, you can either take a placement test in a language school or test your own listening comprehension skills by using recordings available on the internet. Start with listening for beginners, then move on to materials for intermediate learners, and finally those for advanced learners. It should give you an idea of your English proficiency level.
While you're at it, you should make an attempt at this IELTS quiz and see how you fare.
