Making eye contact with members of the audience will make them look at you and keep them engaged in your message. Ask your close friends to sit in different areas of the room so that you won't focus on just one place. Keep your head up: look at the audience, not your shoes.
Smile.
Look like you're excited about running for office. No one will vote for someone who looks like they don't really want the office.
Don't talk too fast.
Everyone has a tendency to rush when they are speaking in public. Make sure your audience can actually understand what you are saying. Force yourself to slow down.
Don't rush off the stage.
After you finish speaking, look at the audience, make eye contact with several people, nod at your opponents, gather up your notecards, and walk off the stage. The last thing you do will make a lasting impression.
Now you're ready for the big day. If you've found a few issues to discuss, come up with some reasonable solutions, and practiced in front of your friends and family, you'll do great. Remember, everyone gets nervous when speaking in front of an audience, and the world won't come to an end if you mess up. Just do your best, be sincere, and have fun. Good luck!