It depends on whether you have a native English teacher/language partner and whether they have an American or British accent. Have a look at this italki site for spoken English tips; http://www.italki.com/knowledge/page/Spoken%20English.htm

As much as you practice with native English speakers the accent you want to learn. American accent with Americans,British accent with British etc. It depends on how often and intensive your practice and how attentive you are while practicing. The more online audio and video resources you use ,the more you expose yourself to listening to the accent and probably have a quicker potential to progress.

I prefer direct conversations with people like you experts, is there any possibilities??

Thanks Sir, i m very glad that many of the experts are taking initiative to answer our small n silly questions.. thanks ones again..

As an American speaking primarily American English since birth, I find the 2 following accents easiest to "hear": American English - Native speakers from the state of Ohio are frequently considered to have the most "neutral" accent and pronunciation. I find this to be the case for myself even though I have never lived in Ohio. British English - "Received Pronunciation" (Queen / King's English) or the same as frequently used on the BBC news network. Personally, as an American, this is the easiest British style accent for me to understand and I do not struggle with the accent at all really. I only occasionally get minor confusion with the different words (our "truck" is their "lorry" for instance). This may not answer your question directly, but trying to mimic either of these two sets of pronunciations and accents should allow you to be understood more widely than learning a local accent specifically.