I am Brazilian too. ( : I agree with Laurie, definetly use a coursebook!
Things that help:
- have a careful plan of the semester. Dates of class and subject that will be given. Dates of tests.
- Always assign homework, even if they don't do it.
Things you can't do:
- show them insecurity (I started teaching when I was 18 and students didn't trust my work in the beginning)
Well, those are the things I can think of at the moment,
Take a look at my website, you might have some ideas for your lessons.http://getenglishlessons.com