What are the most common issues for on-page SEO ranking?

[sonamsharma]

Hello friends,

I want to know that What are the most common issues for on-page SEO ranking?

[drarindamghosh]

Common SEO Issue

Heading Tags Missing
Alt txt
Duplicate Content
Sitemap.xml
Robots.txt

[singhaniaInt]

SEO On page Techniques are

Title
Meta Description
Meta Keywords
URL Structure
Sitemap.xml
Robots.txt
Heading tags
Alt txt
301 Redirection

[amarjyotiadvertising]

Some of the most common on-page SEO techniques are:
Meta tags
Pagination
content length
Keyword density
Title tags, etc.