Humor in your opening will relax you and warm up the audience. Wherever possible, pepper your speech with pertinent stories and incidents that are humorous, even though your topic may be serious. It establishes a connection with the audience. Fear can make you nervous but nerves need not make you fearful. While fear is difficult to channel, nerves, when channeled into energy, can be a positive force bringing vitality and enthusiasm into your speech.
All performers rely on nervous energy to enhance their performance.
You can too. Control your fear rather than allowing it to control you. Your goal is to be comfortable and enjoy speaking before an audience. Create as many opportunities for speaking in public as possible. Join Toastmasters, a community theater group, or take coaching or a class in public speaking or dramatics.