Google Guidelines says that.....

Rich content: - This is applicable for all search engines. If your website has quality content your website will perform awesome on search engines.

Title tag: - Google give high priority to title tag of your web page. Make unique and descriptive title and include important keywords in your title tag. Remember one thing that the keywords which you are using in your title tag should also present in the content of that page.

Description tag: - After the title tag next tag that garbs the Google attention is “description” tag. So try to make unique description for each page of your web site. Also include your important keywords in the description tag.

Note: Description of different pages shouldn’t be same.

Broken links: - As I told in previous articles, broken links in your website can create a problem for search engine spiders to crawl your website. So its batter to check all the links and fix if you find any broken link.

Alt Tag: - Alt tag should be explanatory and accurate that best express your product and services. Alt tag should not be stuffed with keywords.

Static and Dynamic: - Static web sites are easily crawled and indexed by all the search engine spiders. The problem in dynamic website comes when comes at url which contain symbols like? instead of text. For spider it is difficult to keep it in its database.

Limit year link less than 100:- According to one of the Google guideline a given web page should not contain more than 100 links.