Issue a press releases to the media and schools on the availability of local speakers (you), listing their names and telephone numbers. The media release is an announcement to any organization that libertarians are willing to speak to a meeting of their members. The school release should suggest that civics teachers and the like invite local representatives from all the parties to speak to their classes to help get students excited about and involved in civics rather that just read about it.

Speakers don't need a prepared speech. They need only introduce basic libertarian principles, then open for questions. That gets the audience involved and focuses your responses on that which is of interest to your audience. If you are familiar with libertarian principles and remain calm, you can devise good responses for any question.