The number of note cards you should prepare for a persuasive speech can vary based on several factors, such as the length of the speech, the complexity of the topic, and your personal preference. However, a general rule of thumb is to have 5-6 note cards prepared and approved by your teacher before giving your persuasive speech. This should be enough to provide you with a clear outline of your main points and arguments, while also allowing for flexibility and spontaneity during your delivery.