Purchase a Brazilian Portuguese computer program that can get you started on basic vocabulary and grammar. Rosetta Stone is one option. Also look for CDs that allow you to learn in your car (or at home), or books, such as "Portuguese in 10 Minutes a Day," that will show you the basics. Invest in a Portuguese-English dictionary so that you can translate when you need to.
Study Portuguese vocabulary every day. Take at least 15 minutes to half an hour to complete a lesson in your book or on your computer. Review previous vocabulary if you still feel uncomfortable with it.
Make Portuguese flash cards to take with you wherever you go. Review them whenever you have a few free moments, such as waiting for a bus or on your lunch break. Include a few blank cards in your stack so that you can write down an English word or two that you want to translate to Portuguese. For example, you stopped at the library and realized that you didn't know what it was called in Brazil. Make a note and write the Portuguese translation on your card when you get home.
Label objects in your home with sticky notes. Write down the Portuguese names of household items and stick your notes to them. Label the door of each room with the Portuguese name of the room. Each time you see one of these notes, speak the Portuguese vocabulary word out loud to help cement it in your mind.
Expose yourself to Brazilian Portuguese in any way you can. Read Portuguese books or newspapers. Watch Portuguese movies.This will help you with grammar (and pronunciation, if you read out loud) and will also help you increase your comprehension and vocabulary. Listen carefully for words you already know, and keep a Portuguese-English dictionary on hand to look up words that you don't.
Ask a Brazilian friend (or someone else fluent in the language) to help you practice. He can speak to you in Portuguese or point out new vocabulary words for you. Conversational practice such as this will help you learn new Portuguese words and commit words you already know to memory.