We can't deny that American English is most used and it appears everywhere. You hear it on TV, movies, radios or even in the chat! We may not speak perfectly like a native English speaker but with a good accent, you'll become outstanding and more attractive among your peer friends, fellow students from school or colleagues from work.
Learn how Americans speak. With these flash materials, they will teach you how to overcome the problematic sounds like R sound we always face.
I've learned the tricks and helped a lot of friends. I used to be shy to talk with foreigners but now I'm more confident than ever.