Determine whether you want to sound British or American, then listen to good recording. (You can also take my American English Pronunciation lessons here). Learn all the sounds that occur in English - if there is a sound that is giving you trouble, consult a native to help you learn it. Whenever you learn a new word, be sure to learn how to say it in all it's forms (plural, past tense, gerund, etc). When you listen to English for repetition, be mindful of the intonation as well as the sounds. People who otherwise have excellent command of the sounds, are betrayed by a non-native intonation. There's a website called rhinospike.com where you can listen to excellent recording, and you can submit texts to be recorded. My username is JabberVox and I have lots of recording you can listen to. But the most important thing for you to do when you learn English pronunciation is to forget your own language as much as possible and repeat things exactly as you hear them. Let me know if you have any questions. Good luck!

Is it important to reduce your accent?

Hi Mitra. You will never lose your accent. However, the following site has a person say aloud the words or sentence that you have typed in. Choose the accent that you like after you type in your word/sentence. http://www.oddcast.com/home/demos/tts/tts_example.php?sitepal

This is what I did to reduce my accent in some of my languages. When I was learning German and French, what I would do is watch a movie in English that portrayed German or French people. They would speak English in "German" or "French" accents to give the impression that they are speaking their own language. I would imitate that accent (easy because it's done in my own language) and then carry it over to the foreign accent it belongs to. This worked really well for me (and it was fun) and now my pronunciation is regarded as excellent regardless of what language I learn.

Jacob & Farzad, Thanks for your comments.