What are common on-page SEO mistakes?

The most common on-page mistake is writing for a keyword without actually answering the real question behind it, which produces a page that is technically optimized on paper but genuinely unhelpful once someone actually reads it.

Missing or duplicate title tags are another frequent issue, along with thin content that never goes deep enough to be genuinely useful, plus internal cannibalization, where two separate pages end up competing for the exact same term.

Ignoring image alt text and skipping internal links to closely related pages round out the usual list of mistakes, both small fixes on their own that add up quickly across an entire site.

Avoiding these by default, on every page, is a baseline behind automatic SEO software.