The best way is to interact with native speakers and have a lot of listening activity. If it is not possible then speak to youself, acting both as a speaker and listener. Isn't it interesting?
Great advice! As a long time English learner I back up this advice 100%
I would stress the imporance of "reflective" listening which is when you ask yourself do I understand this? can I repeat it? can I repeat it with the same intonation?
Watching movies/TV series and repeating improves listening, speaking and vocabulary too! You have to listen, then pause and repeat what an actor just said, and say the phrase with the same intonation imagining it's you there in that situation!