I think that one should not much worry about American accent as much as you should worry about knowing good english. We all know that Indians have stronger accent than ours but we see that Native American speakers can understand Indians better than they Understand Nepali, now why is that? its becasue Indians speak proper English....There is a huge difference between Bad English and Bad Accent...if you have a good english...Bad accent is no issue at all.

I am not saying improving an accent to a native speaker is not important, it could be important and fun as well but i am just saying it is not important as knowing good English. Learning Phonetics, grammer, phrases, lingos, slangs, and pitch could be helpful in improving your accent.