1. Choose a talk that interests you.
2. Watch the talk without subtitles.
3. Watch it again and take notes.
4. Watch it once more with the transcript in English and compare it with your notes.
5. Take notes of the unknown words and look them up in a dictionary.
6. If you find it difficult to understand the talk, read the transcript in Portuguese and watch it again. Then go back to the transcript in English.
7. Choose some sentences to practice speaking. You can listen to them over and over and repeat imitating the pronunciation and the intonation. This will help you develop or improve your oral skills.