Bom dia. I agree with Redseahorse don't change your accent, it is a waste of time. In general Brazilians have very good pronunciation so it isn't something to worry about, even though a lot of students do worry.
The most common pronunciation error is '-ed' endings so you can work on those, https://www.englishclub.com/pronunciation/-ed.htm
The other one is office, it is "of-fiss" with English pronunciation.
But don't worry about your accent. However if you are moving to Ireland/UK then you will probably have problems understanding the different accents, infelizmente.
There are huge differences in accents, even when you travel 50Km that accent can be totally different.
Check out celebs on YouTube like Danny Dyer [London-ish], Conor McGregor [Dublin], Boxer Carl Frampton [Belfast], footballer Jamie Carragher [Liverpool], comedian Kevin Bridges [Glasgow].
The Glasgow accent can be difficult for natives to understand!