The best thing is to have a native English speaker sit down with you and show you the pronunciation. This has worked for me in a pile of languages. It's not just practising the pronunciation, but also hearing the difference. Ignore the phonemic charts. Good intentions, but they are dodgy. You will sound like a robot. Once you have the basic pronunciation right, just listen and imitate.

I think you need to listen to different topics, pod casts, stories.... also I think you need to a have look at Adrian Underhill's Interactive Phonemic Chart. This will help you to learn the IPA symbols. I suggest you to download the IPA chart from link below: -http://www.onestopenglish.com/skills/pronunciation/phonemic-chart-and-app/interactive-phonemic-chart/

There is a free online talking dictionary of English pronunciation. Just click over the pink words to hear them spoken at : www.howjsay.com/index.php?word. This site has a person say aloud the words or sentence that you have typed in http://www.oddcast.com/home/demos/tts/tts_example.php?sitepal Here is another word pronunciation site: http://www.pronuncian.com