Begin your speech with a personal story that relates to your topic. Your audience needs to know why you are passionate about this subject. "I am against under-aged drinking. My cousin, Bernadette, ..." You have just bonded with everyone in your audience who has lost someone because of a drunken driver. Making a personal connection is important in rhetorical speaking.
Stand confidently but not rigidly. If a podium is present casually, lean against it. Keep your shoulders relaxed and do not let your hands wander aimlessly. Random hand gestures distract from your speech's effectiveness.
Smile and make frequent but brief eye contact with individuals in your audience. Some people will feel like your challenging them if you glance at them too long. Let your eyes rest on a spot in the back of the auditorium (or beyond the last row of seats if you're speaking outside) for 75 seconds out of every two minutes.
The conclusion of a speech is as important as its beginning. Never just abruptly stop speaking. This can confuse your audience and weaken your message. Build to your close by summarizing your previous points. Present another personal anecdote reminding your audience that this topic is personal for you. End with a call to action, such as "Visit this website and sign this ..." Close by thanking your audience for their time.