I ran across this thread and since I am an American, with a Brisilian wife, and her Brasilian family is now mine I decided to expound on my experiences.
An accent is not as much a hindrance, as is the improper construction of sentences. In other words if you can use the correct words in the proper order it is easier for a native to understand, regardless of accent. I am not saying that proper enunciation is not important, but that an accent is not as big a problem as many people think.
In the United States, we Americans may have very noticable and distinct accents from, Boston, New York, Chicago, Atlanta, Los Angles, etcetera, and in some cases a Manhatten, New York accent can be very different from a Brooklyn, or Bronx accent. WE CAN DEAL WITH ACCENTS, even Canadian, British (the worse
), and yes, even the cute Brasilian ones
If you concentrate on the proper use of words, and construction of sentences, while trying to improve your enunciation, and you will be OK.