I think communicating with native speakers or advanced learners will help you a lot with improving your pronunciation.

The best way to actually correct your pronunciation would require a native or near native speaker who was willing to coach you.  There are sometimes sounds that are difficult to hear when your brain is not used to receiving them.  (For example, my recent struggle was with the difference between au-dessus and au-dessous, which have opposite meanings from one another in French.)  Find someone whose own accent you would want to imitate and work with them.  Even better, ask them to work with you on words that are easily confused or hard for speakers of your native language.  I have even heard it advised that you find someone whose voice is in the same range as yours, but that may be a little too persnickety!  (Persnickety means picky about details, by the way!)

Good luck!   There are also some great Youtube videos out there, yes, which will absolutely help with comprehension.  I love cooking shows in my target language!  But then, my target language is French! :) There are some good cooking shows in English too, by the way!

I agree with Hamza.  Rachel´s English is a great channel for American English pronunciation.  I think it is easier to find all her videos through this link though http://rachelsenglish.com/video-categories/

The other site (also not YouTube) that is really good to help with American English pronunciation is http://soundsofspeech.uiowa.edu/english/english.html