Make sure the person at the podium is prepared and is willing and ready to answer questions, including those that might be on the list of expected questions. When I was a reporter, I was called to an evening press conference by a local private school about some upcoming changes. It started late and they handed out a news release, and the spokesman responded by saying the news release says everything we want to say.
The next day, I rewrote the news release, which was standard procedure, and stated that Mrs.________ declined to answer the following questions and listed about four questions that I had asked. I wrote that in responding, she said everything was covered in the news release. It wasn't.
One of the board members called me the next day and said I seem a little irritated the night before. I told him, a press conference was a place where reporters ask questions and expected answers. A press announcement is where a person hands out a copy of the press release and then reads it. The second is a waste of time.
So the short answer to the question--be prepared to answer questions.