Hello

Could you give an idea in details how to do on page optimization?

Here is the list of ON page Optimization things

Always start with keyword selection, research and testing
Meta Description tag
ALT tags
H1 tags
URL structure
Internal linking strategy
Content
Keyword density
Site maps
Usability and accessibility
Track target keywords

To do better on page first search for keywords and put these to you title of site meta tags and write a content having density of 5% of these keywords

Most of the responses are good so I have just added a little extra.

Meta Description tag
Meta keywords
ALT tags
H1 tags
URL structure
Internal linking strategy
Content
Keyword density
Site maps
Usability and accessibility
Track target keywords
Deep Links
Keyword Tags
No spammy or duplicate content

On-page optimization is the process by which various elements on an individual web page are established and structured so that the page can be found by the search engines for a given keyword or key phrase.

There are five elements that really matter to the On-Page optimization process:
1. Page Titles
2. URLs
3. Header Elements
4. Meta Description
5. Meta Keywords