THE QUESTION PERIOD. This can be uncomfortable time, since it's easy to misunderstand a question or - under the pressure of the moment - to forget something you know perfectly well. Don't be afraid, however, to at least try to answer every question.
Controversial seminars are the most fun (at least for the audience). It might be a little threatening to have Bill Thilly or Jacquin Niles hitting you with complex, pointed questions, but this can be important experience for later presentations under less friendly circumstances.
Stay as cool as possible, listen carefully to the questions, give your best answer, and that will be good enough. Try to anticipate some of the questions that might be raised; encourage the audience at your practice sessions to ask difficult questions.
Remember that everyone is on your side.