Pronunciation, honestly, is not as simple as we think. there are two dialects should be considered: American and BritishAmerican dialect may be more familiar among us than the British, because we usually hear American dialect more often by Hollywood movies.For your information, if you have seen "Harry Potter the movies" (any series), that is British accent. Beautiful but bloody hard to understand. But do not worry about that, as long as you practice your pronunciation and hear the correct pronunciation every day the problem will be solved. The ways I practice my pronunciation:
1. Go to www.m-w.com/dictionary
2. Type the word that you want to pronounce.
3. Click the speaker symbol and hear it, again and again.
4. try to pronounce it or the best way is recorded your pronunciation.
5. Compare it with m-w dictionary.
m-w dictionary provides two dialects -British and American- if the sounds of that word are different, usually, there are two symbols of speaker (first symbol is for American and the second one is for British accent, in order).
There is no such a way to mastering English instantly, keep practice every day and you will improve your English gradually or step by step. that is better than you learn many things at once but you "mess it up" at the end.
I hope my tips are helpful, i will be happy to share another tips next time because English is not as difficult as it likes if you learn it on the right track.