As soon as you are given a deadline and topic for your presentation, no matter if It’s 3 weeks out or tomorrow…. Start your research. Let’s say the topic is Corgi’s. Start off defining the subject matter, the diet, health issues, temperament, the cost of ownership and so on. Educate yourself on topic as much as you can.
Ask yourself questions (tough questions). Answer those questions accurately. If you don’t know, do more research until you do.
Look for similar presentations online, what did they cover and what did they not cover?
Remember to keep all your sources for images, charts, articles as you research organized.
Have a friend ask you questions about the topic, the goal here is to become as knowledgeable about the subject matter you are presenting as possible. You don’t need to become a corgi pro, but you do need to convince your audience you are.