Become fluent. Your own fluency is one of the most important factors in teaching Portuguese as a foreign language, particularly if it is not your native language. You will need to answer numerous questions from your students about how the language works and what phrases to use in particular contexts. Talking with native Speakers-speakers is one of the best ways to become fluent in this language; spending extensive periods of time in Portugal and Brazil will help you achieve the perfect level of fluency.
Teach reading. In your classes, give students a good background in basic Portuguese grammar and vocabulary. Early on, start them off reading basic texts in Portuguese. Children's books work well for beginning and intermediate students, while newspapers (many of which can be found online) and blogs or other websites help improve the reading skills of more advanced students.
Teach writing. Have your students correspond with you at least once a week to improve their written skills in Portuguese. Make sure that you explain the different accents used in Portuguese, as well as where to find them on a keyboard. Correct what they send you so that they can learn from their errors and keep improving. If you have time in class, have students write essays and correct the errors they find in one another's work.
Teach listening. Listening is the skill for which it is most important that you as the teacher speak perfect Portuguese. Students should listen to as much Portuguese as possible, preferably spoken by native speakers. If you speak with a Portuguese accent, try to have a Brazilian come into class to demonstrate the different accent, and vice-versa. Play Portuguese music for your students, and show movies featuring Portuguese ("Love Actually" has several scenes with basic Portuguese phrases any beginner should understand) to further improve their listening.
Teach speaking. Make sure that you speak to each student one-on-one at least once a week and that you provide your students with plenty of time for group work and to respond to prompts in-class so that they can practice speaking Portuguese with each other.