It is the %age of your main keywords in the content or text of your webpage. This must be clearly kept in your mind that your main keywords to have the correct keyword density to rank well in Search Engines. The recommended keyword density must be from 3 to 7%, not above 10%. The best keyword density tools
The title is the most important single summary of what a page is all about and therefore carries the highest on-page weightage in terms of Google algorithm. When you go for any searching in Google it is the title of number of websites that appears and by reading the title the user enter the desired website. So, I recommend you that your page title must be “call to action” for users. Title tags should include your main keyword or keyword phrases. The title should ideally be less than 64 characters in length. Every page must have a title tag and each page’s title tag should be different. The title tag should be beginning with the name of your business, company or sites’ keywords that probably attract the users to your website
Words on content
Avoid duplicate content of your webpage. You must have relevant content on your website about your keywords. Choose your main keywords for optimizing that Google finds them important. The average number of words on a page for Google was 943 while Yahoo's average words per page in the top 10 was 1305.
META tags can be very useful for Search Engine Optimizations as a source of information to help them to decide how to list and rank your website. These display your webpage keywords and description. The meta description tag display the description of your page in Google.
The alt attribute is used to define an "alternate text" for an image. You always see ALT text in Internet Explorer that appears by mousing over the images in a yellow box. We can not see this in other browsers like Mozilla etc. Remember, ALT text should always describe the content of the image.
Page headings are created with the tag, in which n is a number between 1 and 5. There are five levels of heading, each using a slightly smaller font size. Many search engines and Web indexes recommend that the use of tags in the webpage will be a huge boost in keyword relevance. The H1 tag is designed to tell the page topic. Because many search engines will use the information from H1 tags, and give it more weight over normal page text, it is a valuable tool for improving search engine placement.