For those of you who are thinking that writing the speech is the easy part, but that you'll never be able to stand up in front of the entire school (or just your class) to actually make the speech, here are some tips for overcoming your anxiety.
Be prepared.
Write your speech and make sure you believe in it. If you are passionate about your message, it will be easier to remember what you want to say. You can use notecards during the speech, but never read it and don't memorize it. You want to sound sincere, and reading your speech or reciting it word for word will make it sound more like an assignment than a speech that you are truly passionate about.
Practice, practice, practice.
Stand in front of a mirror and watch yourself. Don't be a statue; you should move your head and arms in a normal manner. After you're comfortable in front of the mirror, use your parents or your best friend as an audience. Ask for their constructive criticism and take their advice. If your speech is too short, add to it, but don't add things just to fill time. Make sure it's relevant to your campaign. If your speech is too long, cut some things out, but don't elimate your most important issues.
Eat a light meal and drink some water.
You don't want to feel hungy and light-headed while you're speaking, and you don't want your mouth to feel like the Sahara Desert. Just don't eat too much--you don't want to throw up, either.
Dress appropriately.
People are more likely to take you seriously if you are well groomed. Make sure your clothes are clean and pressed, and shine your shoes. If you want people to think you really care about the school, you have to look like you really care about yourself. Avoid high heels--they are uncomfortable and difficult to walk in when you're nervous. Also, don't wear anything that is too tight--you need to be able to breathe.