As we all know,we student learn English as a test tool to get grades.I strongly am against it.We should learn it for love,and pay attention to our pronunciation to contact foreigners better.So how to make our English pronunciation is very important.
It may not be the most effective method, but it's the simplest: Just listen to speakers whose pronounciation of English you like. Via films, TV and radio programmes, podcasts, or web videos. You end up mimicking them.
I also find that singing has a very positive effect. It may depend a bit on the kind of song. I would not recommend the songs of football supporters. ;)