Is it okay to tend to speak in/imitate a standard accent?

Is it okay to tend to speak in/imitate a standard accent like American or British accent?

I live in a country where English is a second language. The majority of people here have a rather strong accent in English. I've always had so much admiration for the US because of how gracious the people tend to be, comfortable environment and stuff, so I want to practice speaking in American accent so when I go to university there in the future (and even work there) I can fit in easily and interact with the people there. However, I always hear people judging on how someone's trying to speak like a native. What's the problem with that? I'm too afraid of people judging me. This kind of hinders me from doing what I want.