Onpage optimization

Please share your Best on-page optimization Technique?

Writing unique articles is the first and foremost thing you need to do. Of course, you need to have the main keywords of your article on your title and URL. Doing this will help you get higher in search results (still, it depends on the keyword's competitions).

And, Google wants to help searchers find sites that provide a great user experience and fulfill their information needs. So sites that publish high quality articles are rewarded with higher search engine rankings as this meets Google's goals.

As long as you have a quality site and you abide by the rules, you will loved by Google. Am I right?

On-page optimization increase the visibility of webpage by optimizing your webpage content. It includes meta tags, alt image tag, h1 tag, site map, robot,txt file, url optimization, internal linking, w3 validation....

I've heard of w3 validation but not given it much thought before as i get really good rankings anyway, assuming i'm targeting attainable keywords.

I Mentioned Some On Page Optimization Activities Are Below:-

Number of Optimized Pages
Keywords Analysis
URL Optimization
Competitor Research
Content & Image Optimization
Meta Tag creation & HTML optimization
Sitemap Creation(XML,HTML)
Robots.txt Creation
RSS Creation
Google Analytics & Webmaster Tools Set Up
Check Keyword Density
W3C Validation
H1,H2,H3,H4 Tags ( Include Your Main Keywords)

Robots.txt creation? What advantages it could give your site?
And how can we create one?

This file gives robots specific instructions.

On-page echniques
1 Tital tag
2 Keywords meta tag
3 home page link
4 Meta description
5 Meta tag
6 Proper Use of Heading Tags
7 XML Sitemap

And, content? That's on page SEO too. Or, at least without it, you don't have much reason for the site.

That's what Google says, though I still see sites that are not best quality content ranking high. Most likely, they are using blackhat tricks to rank high. Slowly, Google is closing the blackhat loop-holes

Slowly and gradually you will see those rankings deteriorate as soon as google notices such practices of those sites.
Yes, good quality content and proper keyword research and use also do not forget to add to the list use of all the formating tags like Heading tags, and Bold Italics and underline, the text color, alt tags for images etc they are also important on page factors for getting a good ranking on the SERPS