13 Common SEO Mistakes You Should Avoid [My Top Picks]

I’ve been working in the SEO world for years, long enough to see a recurring set of mistakes that keep plaguing websites time and time again.

Today, I’m sharing my top 13 picks for the worst SEO mistakes you can make. These are the pitfalls I’ve seen cause significant issues, big drops in rankings, and sometimes irreversible damage.

Let’s jump right in.

1. Slow Page Load Speed

I’ve seen clients whose sites take five seconds or more to load, and they wonder why their bounce rates are through the roof. It’s pretty straightforward: we live in a world where instant gratification is everything.

• Why it matters: According to research, 93% of users will abandon a website if it’s too slow.
• Google’s stance: With Core Web Vitals factoring into rankings, speed is at the forefront now more than ever.

Even a one-second improvement can lead to a 7% increase in conversions. That’s not fluff data; it’s a reality I’ve witnessed repeatedly.

The primary culprits for sluggish speed are unoptimized images, excessive HTTP requests, unminified code, and a failure to use browser caching.

My practical tip: Start by compressing your images, enabling caching, and minifying your JavaScript and CSS files. A single-second difference can make a big difference for both your user experience and your bottom line.

2. Poor Mobile Optimization

In previous years, I would tell clients that mobile traffic was on the rise. Now, mobile traffic is often more significant than desktop for many industries. And yet, some sites still aren’t mobile-friendly.

Let me illustrate:

• A client of mine in the eCommerce sector had a desktop-only site that looked beautiful on a wide monitor. But guess what? Over half their visitors used mobile devices. The bounce rate on mobile was nearly 80%.
• Google’s mobile-first indexing means if your site fails on smartphones, you’re basically invisible to a large portion of your potential audience.

Why this matters: When viewers land on a site that doesn’t work properly on mobile, they leave, which signals to Google that your content is not meeting user expectations.

How to fix it: Make sure your site is responsive. Test it on different device sizes.

Check your site’s PageSpeed Insights mobile score. Pay attention to user experience details like button sizes and font readability to keep mobile users comfortable.

3. SSL/HTTPS Implementation Issues

I still run across websites that haven’t upgraded to HTTPS. I get it—maybe it felt complicated or you thought you didn’t need it because you’re “just blogging.”

But modern browsers now treat HTTP sites with clear warnings.

A Quick Note on Why HTTPS Matters

1. Security: By encrypting data, you protect user information like login details and payment data.
2. Ranking Benefits: Major search engines prefer sites that are secure.
3. User Trust: If your site triggers a “Not Secure” warning, your conversion rates will suffer.

If you handle payments, SSL is simply non-negotiable. Even if you don’t sell anything, not using HTTPS sends a negative signal to both users and search engines.

Make sure every page, image, and script is served over HTTPS to avoid mixed content errors.

4. Keyword Stuffing

This is one of those classic keyword stuffing mistakes I see people repeatedly making. I remember auditing a site that used the same keyword phrase nearly 60 times in a 500-word post. It read like spam, and Google saw it the same way.

Why It’s Bad

• Overusing keywords turns off readers.
• Google’s algorithms detect it, possibly issuing penalties.
• It weakens the trustworthiness of your content.

The best approach is to use your target keyword naturally. Sprinkle in variations and synonyms throughout your piece, and focus on writing for people first. Google is smart enough to understand relevant content without you forcing the same phrase in every other sentence.

5. Low-Quality Content

Many still think they can pump out blog posts of 300 words filled with scant value. That might have worked, barely, ten years ago. Not now.

Today’s search engines favor content that shows:

• Experience: Real-life or practical knowledge on the subject.
• Expertise: Well-researched insights.
• Authoritativeness: Recognized standing in the subject area.
• Trustworthiness: Honest, accurate content backed by reliable sources.

If your content is thin, irrelevant, or poorly written, it can hurt your SEO.

Address user intent, answer specific questions thoroughly, and put extra effort into covering the topic fully. That approach resonates with both readers and search engines.

6. Keyword Cannibalization

I once worked with a company that had a dozen pages all targeting the exact same keyword, and they couldn’t understand why their rankings were erratic. That is a textbook case of keyword cannibalization.

One site, multiple pages, and the same target keyword creates confusion for Google. Which page should it rank? Sometimes Google ranks a less suitable page, or none at all.

To avoid this problem, plan each page with its own primary keyword before publishing.

Consolidate similar pages and rewrite them so each focuses on one main idea. If two pages must stay live but have overlapping content, use canonical tags.

7. Missing or Duplicate Meta Titles and Descriptions

Meta titles and descriptions are prime real estate. Yet, I often find entire websites with default or missing meta tags. Sometimes the same title and description are repeated across multiple pages.

Why This Hurts:

• Rankings: Search engines use your meta title to understand what your page is about.
• Click-Through Rates (CTRs): An engaging meta description can be what makes someone choose your link over another.

A good practice is to craft unique, concise, and appealing meta titles that include your main keyword. For descriptions, give visitors a reason to click—mention key benefits or solutions your page offers.

Even though meta descriptions are not direct ranking factors, they significantly influence user behavior in the search results.

8. Poor Header Structure

To put it simply, your HTML headers (H1, H2, H3, and so on) help both readers and search engines follow your content. I have seen sites that use only H2 headings, ignoring a logical hierarchy. That creates a confusing layout.

A proper header structure:

• Provides a clear outline of your article.
• Helps screen readers and accessibility tools navigate your page.
• Offers search engines a guide to the importance of different sections.

If your headers are disorganized, your content will be harder to follow, which might impact your ranking. It is helpful to break down complex information into smaller sections that are easy to scan.

9. Ineffective Internal Linking

I can tell when a site isn’t using an effective internal linking strategy. This can result in pages that are isolated and hard for both users and search engine bots to find. It might also mean a site hierarchy that lacks a logical flow.

A strong internal linking strategy helps to:

• Spread link value throughout your site.
• Allow users to navigate to related content easily, increasing the time they spend on your site.
• Provide search engines with clues about how your content is connected, which aids in indexing.

When done well, internal links reduce bounce rates because visitors have a clear path to follow from one page to another.

10. Robots.txt Mistakes

If you wake up one day to find your site traffic has dropped sharply, one possible cause might be your robots.txt file. A single mistaken “Disallow” rule can block important sections—or even the entire site—from Google’s crawlers.

Common errors include:

• Blocking important pages by mistake.
• Blocking crucial scripts or CSS, which can interfere with proper indexing or rendering.
• Not updating the file after changes to your site structure.
• Using wildcards in a way that blocks too much.

It is a good idea to review your robots.txt file whenever you launch a new design, add major sections to your site, or change hosting providers.

11. Too Many Non-Indexed Pages

A scenario I encounter often is a large site with thousands of pages where many don’t appear in Google’s index. If Google doesn’t know about your pages, they might as well not exist.

Some common causes are:

• Noindex tags mistakenly left in place after a redesign.
• Server or crawl errors.
• Duplicate content, which can lead some pages to be hidden.
• Misconfigurations in robots.txt or .htaccess.

I regularly check Google Search Console to ensure all important pages are indexed. If they aren’t, it is important to identify and address the issue quickly.

One simple solution is to create and submit an updated XML sitemap that guides Google to the pages you want them to index.

12. Duplicate Content

Duplicate content can cause real problems. Google’s algorithm may have difficulty deciding which version to rank, ending up ignoring both pages or selecting a less optimal page. It can also split inbound links between duplicates, weakening their overall impact.

Duplicate content may occur if:

• Your site is accessible under different URLs (for example, www versus non-www or HTTP versus HTTPS).
• Product descriptions or other content is copied verbatim.
• Archive pages or taxonomy pages are duplicated in WordPress without using canonical tags.

A practical way to prevent this is to properly set up canonical tags, choose a preferred URL version (such as HTTPS with or without www), and ensure internal links consistently use that version.

13. Poor Taxonomy and URL Structure

I work with many WordPress sites, and it is surprising how often random categories and tags create chaos in Google’s index.

Some typical issues are:

1. Excessive Tagging: Every post gets more than 10 tags, leading to many similar archive pages.
2. Haphazard Categories: Lack of logical grouping makes it hard for users and search engines to understand the structure.
3. Confusing URLs: Unfriendly URL formats like “yoursite.com/p=123” or overly repetitive categories.

A better method is to keep tags focused but limited, establish a clear hierarchy with main categories and subcategories, and create clean permalinks that match the content.

Quick Reference Table

Sometimes it is helpful to see everything at a glance. Here is a summary of the 13 mistakes and their main impacts: