Do not underestimate the language barrier ...
... Brazilians speak Portuguese, and Portuguese IS NOT Spanish.

If you speak Spanish, it may be possible to communicate effectively if both parties make an effort, but keep a dictionary or interpreter handy.

Many Brazilians speak English, but few have your level of fluency.  Do not proceed unless you are convinced that the other parties understands you very clearly, either personally or through an interpreter that you trust.

Be careful when Brazilians tell you they understand you "perfectly" ...
... perform some small tests ...
... egos rule supreme, do not corner people on this subject.

It may be more productive to have several smaller meetings as opposed to a marathon session.  If there are many issues to be resolved, do it in small doses, avoid touchy points during meals.  Avoid being pushy (a stereotype of Americans).  Have some flexibility to accommodate last minute changes.

Always clearly document everyone's commitments and expectations ... distribute copies if they do not write down their promises.

Agree on verifiable milestones; track performance so corrective action can be taken in a timely manner.

Business dinners are late (between 8 and midnight) and long.  Food in Brazil is excellent, and service (even in simple restaurants) is much better than anything you are used to in the U.S.  And Brazilian waiters do not have that horrible American habit of clearing dishes before ALL guests are finished.

Talk to the waiter, ask his name, etc., and you will be treated like a king.  A 10% tip is added to your check; leave some more if you want to reward extra good service.

Water : Drink bottled water, available everywhere.  Ask for "água mineral", available plain ("sem gás") or carbonated ("com gás").

Contracts are signed by companies - but are negotiated by individuals.

Brazilians have a more informal way of doing business, with great emphasis on the personal side.  They want to trust you before getting serious; you should respect and accept that.  The success of your business ventures will depend just as much on who you are as it does on the deal itself.

Three-piece suits carry an "executive" connotation, whereas two-piece suits are associated with office workers. Conservative attire for women in business is very important. Also make sure your nails are manicured.

On clothing, some Brazilian businesspeople will dress fairly casually at their office but they generally expect visitors to wear appropriate business attire. When deciding what to wear remember that in the north-east States, suits are rarely worn because of the heat. In the South, however, lightweight suits made of natural fibres are fine for most of the year. A dark lightweight suit will be useful for more formal evening appointments. Dinner jackets are rarely needed. Few restaurants require a jacket and tie to be worn. Women wear light cotton dresses in summer. During the winter, light woollen clothing is suitable for Southern Brazil but British summer clothing is more appropriate for Rio de Janeiro and the north-east. Brazilian women are very fashion conscious. Sunglasses are recommended for everyone.

The colors of the Brazilian flag are yellow and green. Avoid wearing this combination in any fashion.