Common SEO Mistakes to Avoid

Even experienced developers make SEO mistakes. This lesson covers the most common issues and how to fix them.

Technical Mistakes

1. Blocking Crawlers

# Bad: Blocking everything
User-agent: *
Disallow: /

# Good: Only block what's necessary
User-agent: *
Disallow: /admin/
Disallow: /api/
Allow: /

Check your robots.txt: Verify crawlers can access important pages.

2. Missing or Duplicate Titles

// Bad: Generic title
export const metadata: Metadata = {
  title: 'Page',
}

// Good: Unique, descriptive title
export const metadata: Metadata = {
  title: 'SEO Best Practices for Next.js | Your Site',
}

Every page needs a unique, descriptive title.

3. No Meta Description

// Bad: Missing description
export const metadata: Metadata = {
  title: 'Product Page',
}

// Good: Compelling description
export const metadata: Metadata = {
  title: 'Premium Running Shoes | Your Store',
  description: 'Discover our collection of premium running shoes. Free shipping on orders over $50. Shop now for the best selection.',
}

4. Broken Canonical Tags

// Bad: Wrong canonical
export const metadata: Metadata = {
  alternates: {
    canonical: 'https://example.com/old-url', // Points to wrong page
  },
}

// Good: Correct self-referencing canonical
export const metadata: Metadata = {
  alternates: {
    canonical: 'https://example.com/current-page',
  },
}

5. Missing Alt Text

// Bad: No alt text
<Image src="/product.jpg" alt="" width={400} height={300} />

// Good: Descriptive alt text
<Image
  src="/product.jpg"
  alt="Red running shoes with white sole, side view"
  width={400}
  height={300}
/>

Content Mistakes

1. Thin Content

Pages with very little content often don't rank well.

Signs of thin content:

• Pages with only a few sentences
• Duplicate content across pages
• Auto-generated content without value

Solution: Provide comprehensive, valuable content that answers user questions.

2. Keyword Stuffing

Bad:
"Our SEO services provide the best SEO for your SEO needs.
Our SEO experts use SEO techniques for SEO success."

Good:
"Our search optimization services help your website rank higher.
Our experts use proven techniques to improve your visibility."

3. Ignoring Search Intent

Match content to what users actually want:

Query	Intent	Content Type
"buy running shoes"	Transactional	Product page
"best running shoes 2024"	Commercial	Review/comparison
"how to clean running shoes"	Informational	How-to guide
"nike.com"	Navigational	Brand page

4. Not Updating Old Content

Old content can become outdated and lose rankings.

Best practices:

• Review content annually
• Update statistics and examples
• Fix broken links
• Add new relevant information

Performance Mistakes

1. Unoptimized Images

// Bad: Large unoptimized image
<img src="/huge-photo.jpg" />

// Good: Optimized with next/image
<Image
  src="/photo.jpg"
  alt="Description"
  width={800}
  height={600}
  quality={80}
/>

2. No Lazy Loading

// Images below the fold should lazy load (default in next/image)
<Image
  src="/below-fold.jpg"
  alt="Feature"
  width={400}
  height={300}
  loading="lazy" // Default behavior
/>

// Above-fold LCP images should NOT lazy load
<Image
  src="/hero.jpg"
  alt="Hero"
  width={1200}
  height={600}
  priority // Disables lazy loading
/>

3. Render-Blocking Resources

// Bad: Blocking script in head
<script src="/heavy-script.js" />

// Good: Load after page is interactive
<Script
  src="/heavy-script.js"
  strategy="afterInteractive"
/>

4. No Caching Strategy

// Implement proper caching
export const revalidate = 3600 // Cache for 1 hour

// Or use fetch caching
const data = await fetch(url, {
  next: { revalidate: 3600 }
})

Mobile Mistakes

1. Not Mobile-Friendly

Google uses mobile-first indexing. Ensure your site works well on mobile:

• Responsive design
• Touch-friendly buttons (48px minimum)
• Readable text without zooming
• No horizontal scrolling

2. Intrusive Interstitials

Avoid popups that block content on mobile:

// Bad: Full-screen popup on page load
useEffect(() => {
  showFullScreenPopup()
}, [])

// Good: Non-intrusive banner
<div className="fixed bottom-0 p-4 bg-blue-100">
  <p>Subscribe to our newsletter</p>
  <button>Subscribe</button>
  <button>No thanks</button>
</div>

3. Different Content on Mobile

Mobile and desktop should have the same content. Don't hide important content on mobile.

Link Mistakes

1. Broken Internal Links

Regularly audit for 404 errors:

// Create a custom 404 page
// app/not-found.tsx
export default function NotFound() {
  return (
    <div>
      <h1>Page Not Found</h1>
      <p>The page you're looking for doesn't exist.</p>
      <a href="/">Return Home</a>
    </div>
  )
}

2. Poor Internal Linking

// Bad: No context
<a href="/guide">Click here</a>

// Good: Descriptive anchor text
<a href="/seo-guide">Complete SEO guide for beginners</a>

3. Nofollow on Internal Links

// Bad: Nofollow on internal link
<a href="/important-page" rel="nofollow">Important Page</a>

// Good: Let PageRank flow internally
<a href="/important-page">Important Page</a>

Only use nofollow for:

• User-generated content
• Paid/sponsored links
• Untrusted external links

Structured Data Mistakes

1. Invalid JSON-LD

// Bad: Invalid JSON
const schema = {
  '@context': 'https://schema.org',
  '@type': 'Article',
  // Missing required properties
}

// Good: Complete, valid schema
const schema = {
  '@context': 'https://schema.org',
  '@type': 'Article',
  headline: 'Article Title',
  author: {
    '@type': 'Person',
    name: 'Author Name',
  },
  datePublished: '2024-01-15',
  image: 'https://example.com/image.jpg',
}

2. Mismatched Data

Structured data must match visible content:

// Bad: Price in schema doesn't match page
const schema = {
  '@type': 'Product',
  offers: {
    price: '29.99', // But page shows $39.99
  },
}

SEO Audit Checklist

Run through this checklist regularly:

Category	Check
Crawlability	robots.txt allows important pages
Crawlability	XML sitemap submitted and valid
Crawlability	No orphan pages
On-Page	Unique titles on all pages
On-Page	Meta descriptions present
On-Page	H1 tags used correctly
On-Page	Images have alt text
Technical	Canonical tags correct
Technical	Hreflang tags (if multilingual)
Technical	HTTPS enabled
Technical	Mobile-friendly
Performance	Core Web Vitals pass
Performance	Images optimized
Content	No thin/duplicate content
Links	No broken links
Links	Good internal linking

Summary

In this lesson, you learned:

• Common technical SEO mistakes
• Content mistakes that hurt rankings
• Performance issues to avoid
• Mobile optimization requirements
• Link building best practices
• Structured data validation
• How to audit your site regularly

Congratulations on completing this SEO course! You now have the knowledge to build SEO-optimized Next.js applications.