Early in the presentation ask the audience if they can all hear you. Pay attention to the correct pronunciation of words and try to clearly enunciate. Be careful of the pace of presentation. Practice use of the pointer. When using a laser pointer, be sure it can be seen by the audience at the rear of the room.
Every seminar concludes with such a session.
You can prepare by trying to anticipate questions which might be asked. Often the audience will ask questions concerning material at the end of the seminar. The audience may want clarification of a main point, experimental procedure, or predictions on unresolved problems. It is very important to be honest in answering these questions. If your answer is a conjecture then tell them so.