You also need to understand what the audience's attitudes may be toward you. Will they be suspicious or hostile? Or, will they be friendly and welcoming? Are they anxious to hear what you have to say? Or, are you going to be discussing something they could care less about? Of course, each listener will have his or her unique attitudes towards your subject so you can't predict each individual's responses. Even still, getting a general view of the audience at large will provide some distinct guidelines that will help you shape your presentation.
That said, you do need to know if there are certain key people in the group that you need to win over. Some groups have members who operate as leaders and those people can shape how your message is received. If that's the case, you may consider directing a portion of your message to that person without making it too obvious to the other audience members.
As you continue to analyze your audience, consider the occasion and the environment. You need to do this because the setting may also influence how open the audience is going to receive your message. To get a handle on the environment, find out the answers to the following questions:
Once you get the responses to these questions and others you'll be able to eliminate as many unknowns as possible. You should also check out the space prior to your talk so you can determine if the answers to your questions were accurate or discover if things have recently changed. It will also allow you to make last minute changes to your presentation if you find some major problem—such as a bad Internet connection, for instance.