One of the things that is difficult for English speakers to deal with when learning Portuguese is the feeling that Portuguese can be really rude. Linguistically and culturally, Brazilian Portuguese has some important differences from English that one needs to be aware of.

First of all, making requests in Brazilian Portuguese are generally made with the imperative, which frequently lack por favor (please). This can seem rude for English speakers, since we are accustomed to using “please” even in basic, informal requests.

For example: Segura isto para mim. Hold this for me.
Fecha a porta. Close the door.
Dá ai. Give it to me / hand it over.

Adding “por favor” at the end of a request isn’t wrong, and is certainly polite, but isn’t necessary unless in a formal situation.

Also, when ordering at a restaurant, it’s common to use querer (to want) in the present simple form to order, which for English speakers may seem rude.

For example: Eu quero a salada. Literally: I want the salad. Translated: I’ll have the salad.
Ela quer a pizza com presunto. Literally: She wants the ham pizza. Translated: She’d like the ham pizza.

Again, adding a “please” at the end never hurts, and will certainly make your waiter feel a bit more respected, but again, is not necessary.

Finally, there are certain expressions in Brazilian Portuguese that English speakers may be taken aback by since upon first glance they seem rude.

For example: Você que sabe. This translates roughly as “it’s up to you,” but literally translates as “You’re the one who knows.” For an English speaker literally translating the phrase, it’s easy to be taken aback. But look at how it’s used:
Vamos de metrô ou de ônibus? Are we taking the subway or the bus?
Você que sabe. It’s up to you.

Another phrase that takes getting used to is “calma ai.” This translates as “wait a second,” or “hold on” but for an English speaker, the “calma” part sounds like “calm” and one gets the sense that it means “calm down.” But don’t worry–it doesn’t! Take a look:
Podemos ir agora? Can we go now?
Calma ai, esqueci minha bolsa. Wait a sec, I forgot my bag.

If using “calma ai” still weirds you out, you can also use “espera ai” which means the same thing. In Brazilian Portuguese, though, it usually comes out sounding like “perai.”