The Key Mistakes to Avoid When Writing a Pitch Deck

Delta Scale

September 10, 2025

Skills & Career Development

Creating a strong pitch deck can open doors to investors, partners, and opportunities — but common mistakes often weaken even the best ideas. From overloading slides with data to neglecting the story behind the startup, founders frequently miss the chance to inspire. In this post, we break down the key pitfalls and how to avoid them so your deck not only informs but also captivates.

The Key Mistakes to Avoid When Writing a Pitch Deck

A pitch deck is more than just slides; it’s your story, your credibility, and often your first impression with investors, partners, or clients. While great pitch decks can spark interest and open doors, weak ones can close them quickly. After reviewing countless decks, here are the most common mistakes founders make — and how you can avoid them.

1. Overloading with Information

A pitch deck isn’t a business plan. Too many slides, walls of text, or dense financial tables overwhelm your audience. Investors want clarity, not clutter.
Keep it simple: aim for 10–15 slides with focused key points. Use visuals and charts instead of paragraphs.

2. Missing the Story

Facts and numbers are important, but without a compelling narrative, they won’t stick. Many founders jump straight into product features without explaining the bigger “why.”
Start with the problem, show the pain point, then explain how your solution creates real value.

3. Ignoring the Market Context

A common mistake is claiming the market is “huge” without providing credible data or showing how you’ll capture it.
Break down your Total Addressable Market (TAM), Serviceable Addressable Market (SAM), and Serviceable Obtainable Market (SOM). Show that you know your niche and entry strategy.

4. Weak Value Proposition

If you can’t clearly explain why your product is different — and why it matters — investors will lose interest. Buzzwords and vague claims like “revolutionary” or “game-changing” don’t convince anyone.
Craft a sharp, one-sentence value proposition that highlights your unique advantage.

5. Forgetting About Competition

Some founders say, “We have no competitors.” That’s a red flag. Every problem has existing solutions, even if they’re indirect.
Acknowledge your competitors and highlight your edge. Show why customers would switch to you.

6. Unrealistic Financials

Projecting exponential revenue growth without explaining assumptions is a major credibility killer.
Be ambitious but grounded. Include key metrics (CAC, LTV, margins) and make sure numbers align with your business model.

7. Neglecting the Team Slide

Investors back people as much as they back ideas. A deck that treats the team as an afterthought misses the chance to showcase credibility.
Highlight the relevant experience, skills, and passion of your core team.

8. Poor Design & Delivery

A great idea can get lost in bad visuals, inconsistent fonts, or overcrowded slides. Likewise, reading directly from the slides during the pitch kills engagement.
Use a clean, professional design. Keep slides visual and practice telling the story confidently without over-relying on text.

9. Not Asking for Anything

Some decks end without a clear “ask.” Investors want to know what you need and how the funds will be used.
Be specific: “We are raising €500k to expand product development, hire two engineers, and grow marketing in Germany.”

Final Thought

A pitch deck is not about dumping data — it’s about clarity, credibility, and story. Avoid these common mistakes, and your deck will not just inform, but inspire.