On page optimization refers to all activities which you can do on your site for search engine ranking making it search engine friendly. Off page and On-optimization both are essential for search engine optimization of website. Although Onpage optimization is less important as compared to off page SEObut still it is absolutely necessary for increase traffic, usability and search engine positioning.
We have made a list of On-page activities or factors which you  must ensure have been done to make it more search engine and users friendly. Here is the On Page SEO checklist.
  1. Perfecting Keyword Research and Targeting
  2. Creation of descriptive HTML Title tags with your keyword and Brand – one of the most important factors in SEO
  3. Ensure title tag is  less than 65 characters including spaces.
  4. Ensure description tag is less than 155 characters including spaces.
  5. Creation of meta description tags of the page including tagged facts and  structured data about the Page.
  6. Creation of search engine friendly URL with relevant keyword or phrase with shorter length.
  7. Creation of static URL, avoid dynamic URL and session ID
  8. Creation of Meta Robots to allow the search engine to index the web page
  9. Creation of Meta Keywords Tags although not much considered by search engines.
  10. Creation of <Language> meta tag If your site is language-specific,.
  11. Use Canonical URL Tag  to avoid duplicate content on your site from search engines indexing.
  12. Optimization of Global Navigation Link Structure
  13. Optimization of Breadcrumb Navigation Links Structure
  14. Optimization of Alternative Link Structures
  15. Ensure the use of three essential structures in site building i.e sequences, hierarchies, and webs.
  16. Decision on percentage of internal links on a page
  17. Decision on  link location in Top menu, sidebar and footer.
  18. Use of varied  anchor text in Internal linking
  19. Decision on number of Internal links within the content.
  20. Use of nofollow and dofollow Links
  21. Adding some outbound links on a page which has value to your site users.
  22. Make analysis of website ability to support browsing by testing it interactively
  23. Content optimization
  24. Checking Keyword repetition is done within reasonable parameters.
  25. Checking Keywords placement on important locations of the page also known as Content Structuring
  26. Ensuring optimum keyword density
  27. Use of Keyword variations including synonyms, singular and plural forms.
  28. Optimizing your sub- titles and proper use of header tags H1, H2 and H3
  29. Creating keyword prominence, frequency and proximity
  30. Use of Hyphens or underscore in keyword separation.
  31. Use of image title and an “Alt tag”.
  32. Creating image name with your keyword or pharase
  33. Using a Keyword in bold/strong
  34. Use on the targeted keyword term/phrase in Italic/Emphasized
  35. Avoid Using frames
  36. If flash used do add the additional description in text.
  37. Proper use of Java script as search engine cannot index content in Java script
  38. Ensure proper site accessibility
  39. Ensure IP address is not blacklisted
  40. Check For broken links, 404 errors and dead links
  41. Creation of Sitemaps in text, HTML, RSS, ROR and XML
  42. Creation and Validation of Robots.txt File
  43. Creation of 310 and 302 redirection by using .htaccess file
  44. Optimizing your 404 page
  45. W3C css validation, checking your cascading style sheets (css) and (x)html documents with style sheets
  46. Google Analytics Account Set
  47. Create RSS feed and display RSS feed on website
  48. Create and Manage Google, Bing and Yahoo Webmaster Tool
  49. Google page speed test to evaluates the performance of web pages
  50. Google video sitemap generator
At last do not over optimize the  page for your keyword or phrase. Try to make your page optimization keeping in view your users not the search engines. You must check that there should not be any hidden links or text. Do check clocking also.