Following are  few essential points which are to be kept in mind while optimizing SEO  
 
How informational is a  page:
 
Amount of text on a web pages is  matters a lot to get ranked by search engine a page having high amount of  information will be preferred and ranked higher rather than a page having a  small amount of information over the page. Generally, we should try to increase  the text content of our website in the interest of SEO. The optimum page size is  500-3000 words (or 2000 to 20,000 characters). Well when amount of text increase  it would likely to increase the search queries for that page and finally it  would help out in increasing the number of visitors.
Number of  keywords on a page
 
Keywords  play an important role we must use at least three to four times in the page  text. It may vary from page to page all depends on the size of the page Keyword  phrases are also very worth full. We can get best results ifa keyword phrase is  being repeated many times in a web page text and all keywords in the phrase  should be arranged in exactly the same order
 
Where o Locate the  keywords on a page
 
 Well it  is very clear and simple that keyword should be near to the beginning of the  documents, the closer a keyword or keyword phrase is to the beginning of a  document, the more considerable it becomes for the search engine.
 
One page – one keyword  phrase
 
 For  maximum seo try to optimize each page for its own keyword phrase. Sometimes you  can choose two or three related phrases, but you should certainly not try to  optimize a page for 5-10 phrases at once. Such phrases would probably produce no  effect on page rank. 
 
Seo and the Main  page
 
 Optimize  the main page of your site (domain name, index.html) for word combinations that  are most important. This page is most likely to get to the top of search engine  lists. My seo observations suggest that the main page may account for up to  30-40% percent of the total search traffic for some sites 
 
Keyword density and  SEO
 
   Keyword page density is a  measure of the relative frequency of the word in the text expressed as a  percentage. For example, if a specific word is used 5 times on a page containing  100 words, the keyword density is 5%. If the density of a keyword is too low,  the search engine will not pay much attention to it. If the density is too high,  the search engine may activate its spam filter. If this happens, the page will  be penalized and its position in search listings will be deliberately lowered.  
 
Text format and  seo
 
 Search  engines pay special attention to page text that is highlighted or given special  formatting. We recommend:
   - use keywords in headings. Headings are text  highlighted with the «H» HTML tags. The «h1» and «h2» tags are most effective.  Currently, the use of CSS allows you to redefine the appearance of text  highlighted with these tags. This means that «H» tags are used less than  nowadays, but are still very important in seo work.;
 
«TITLE» tag
 
This is one of the most important  tags for search engines. Make use of this fact in your seo work. Keywords must  be used in the TITLE tag. The link to your site that is normally displayed in  search results will contain text derived from the TITLE tag. It functions as a  sort of virtual business card for your pages.
 
Some other very critical  components are as follow:
 
-  Ageing of your website  
-  Quality Contents of your  website  
-  Back linking over your  website  
-   Useful information over your  website  
-  Design and layout of your  website