12 Public Speaking Mistakes to Avoid

Public speakers need to be mindful of their speaking habits, especially in the workplace. Below are 12 common mistakes excerpted from the Amazon best-selling book Knockout Presentations.

Common Public Speaking Mistakes

• Lack of Preparation

  Many presenters spend insufficient time preparing. Effective delivery requires 90% preparation—hours of strategizing, structuring the message, planning visuals, and practicing until the delivery feels seamless and natural.

• Lateness

  Arriving 10 minutes before a presentation is too late. Arrive 30–60 minutes early to assess the room and greet the audience. Always end on time, as audiences prefer finishing early over running late. Practice and time your talk, accounting for a 10% longer runtime in front of an audience.

• Not Knowing the Audience

  Tailor your presentation to the audience. Create a listener profile by considering demographics, preferred information delivery, and attitudes. Determine whether the audience is specialist or generalist, and research past high-rated speakers to align with expectations.

• Projecting the Wrong Image

  First impressions are visual. Your attire, tone, and language should align with the audience’s expectations. For conservative audiences (e.g., financial corporations), dress formally. For creative audiences, a more casual or fashion-forward approach may work.

• Using Visual Aids Ineffectively

  Slides should aid, not dominate, your presentation. Avoid text-heavy slides; use photos, graphics, videos, and keywords instead. Practice with a remote and rehearse the entire deck to avoid fumbling.

• Including Too Much Material

  Avoid overwhelming the audience with excessive information. Focus on what they need to know, not everything you know. Remember: "The mind can absorb only as much as the seat can endure."

• Using Inappropriate Humor

  Humor can engage audiences but must be used carefully. Avoid jokes that may offend in multicultural or politically correct settings. Self-deprecating humor or playful interactions with the audience are safer alternatives.

• Speaking in a Monotone

  Monotone delivery disengages audiences. Use vocal variety, hand gestures, and emphasis on key words. Enthusiasm is contagious—get excited to keep the audience engaged.

• Not Building an Audience Relationship

  Talking at the audience with facts alone won’t build rapport. Use storytelling to create likability and trust. Pause, listen, and connect to make the presentation interactive.

• Lack of Focus

  Define your outcome by completing this sentence: "At the end of the presentation, the audience will ______." Start with the outcome to maintain clarity and focus throughout.

• Starting with Details

  Beginning with details confuses the audience. Provide a high-level overview first, then sandwich details in the body of the presentation. Structure your speech with a clear opening, body, and conclusion.

• Being Speaker-Centered

  The most common mistake is making the presentation about you. Instead, focus on the audience’s needs. Start with a hook or benefit statement, address their issues, and present your solution to keep them engaged.

About the Author

Diane DiResta, CSP, is Founder and CEO of DiResta Communications, Inc., a New York City consultancy serving business leaders who deliver high-stakes presentations. She is the author of Knockout Presentations: How to Deliver Your Message with Power, Punch, and Pizzazz, an Amazon.com category best-seller, and has spoken on four continents. Visit www.diresta.com for more information.