The fear of being accidentally rude
English has one "you" and no decisions to make. Brazil has você and hands it to everyone. Portugal has a graded system that nobody writes down, and getting it wrong is the thing most learners actually worry about.
The good news is that it comes down to four options and one word to avoid.
Tu, and who gets it
Tu is the informal form, and informal means something narrower here than you might assume.
- Family and close friends.
- People your own age in a relaxed setting.
- Children and teenagers.
- The dog.
It has its own verb endings and they are not optional: Tu queres?, Tu foste? Use Brazilian third-person forms with a friend and you sound oddly distant, as though you were keeping them at arm's length.
Você, and why to leave it alone
This is the one that catches people. It looks like the safe middle option and it is not.
Addressed directly as você, a lot of Portuguese people hear something cool and clipped, and some hear a person talking down to them. It occupies an awkward space: not warm, not respectful, just distant.
You will hear it in some regions and from some generations. As a learner, the simplest rule is not to say it at all. You lose nothing, because there is a better option.
Just drop the pronoun
Too distant for tu, unwilling to use você. So you use neither, conjugate in the third person, and leave the subject out.