Most vital aspects of on page optimization:-

1.Domain registration.

2.Content optimization:-All will work well if this thing works well.Contents of each and every webpages should be unique and informative. Briefly describe the features or theme of a page and don't write any irrelevant contents.

3.Title:-Each and every webpages should have an unique title.This title appears below the address bar of any browser window.Look at the tabs ,whatever you can see there is the title of a page.It is first parsed by search engines to determine the content of any webpage.None of the pages should be left untitled.Untitled page never gets any traffic.

4.Meta tags:-This is the most important tag of a page's HTML source code.As it contains keywords relevant to the contents of a page.Content attribute of Meta element should contain short but descriptive information about the website or the webpage.

IMO, all the on-page factors are equally important and should be worked on. I believe that Domain Registration is not one of the on-page optimization factors.

Nice post.I agree with your all points.Also pay attention on following things like:
1.Headlines & text decoration
2.TITLE and ALT Attributes
3.Keep it up-to-date

On Page Search Engine Optimization is the best and effective way to promote your business online and also to promote the website of your company. On the side, very good factor for the placement of your website to learn more about the major search engines such as Google, Yahoo and Bing. On page optimization refers to as the text and content on your website.