When I meet new people who want to improve their English, they always start with "Oh, I feel good reading and writing in English, but when the time comes to talk to somebody, I can't understand a word". So, these people find it challenging to listen and respond which leads them to the idea of having English lessons a couple of times a week.
Your teacher can help you to improve your skills by giving you tips and tricks and by controlling your practice. But the majority of people have English lessons only once or twice a week which gives us two-three hours practice of a foreign language a week. That is simply not enough practice time to improve.
What if you need to improve your listening skills in 4 weeks because you have a business meeting or just want to understand native speakers in their environment?
All you need to do is listen.
But listen actively. Take a pen and a piece of paper, write down any unknown words and general ideas.
Download an English radio app, find your favorite radio station and listen to it a couple of hours a day. Choose a radio station that also provides music. Don't listen to "talk stations" all the time. It will make you bored, for sure. I love the Irish accent, so I found a radio station that has nice music and radio hosts with a great sense of humor and a beautiful accent.
Find podcasts in English. Listen to experts in your sphere who live in an English-speaking country. Not only it can improve your listening skills, but also it may give you an insight on how to socialize overseas. Again, the accent choice is very important here.
TED talks. Great source of listening material on a wide variety of topics.
Listen to audiobooks in English. You can choose whether you'd like to listen to fiction or non-fiction, American or British accent, etc. However, some people find listening to audiobooks a great help against insomnia. So, make sure you can actively listen and take notes.
YouTube. Find a vlogger that has similar tastes in life as you do. Watching someone who has a similar life to yours and who is continually speaking about it may also teach you some additional vocabulary to describe your life, tastes, interests, etc. Or you can find someone who has a life completely different from yours. It's always up to you and your mood.
Last but not the least, find free listening tests online. Various websites offer to test your skills before exams. It will give you a great opportunity to see your current level and practice. My advice is to take the same test couple of times to see where exactly you make mistakes or feel unsure and then repeat it in a couple of days or weeks to see your progress.
These are the main pieces of advice I would like to give you today. Keep practicing and remember that everything is in your hands.