Use Correct Doctype
Document type defination(DTD) is also know as Doctype, doctype informs the browser how to interpret the content of the page. If the the doctype is not declared, the browser assumes you don’t know how to code, and goes into quirks mode. If you know what you are doing and include a correct HTML doctype, your page will be rendered in standards mode.
Use correct doctype, for example your using strict doctype and you use used align in in div tag or in p tag then doctype you used is not correct because align attribute is deprecated in strict doctype.
Make the code prettier than the design
When building the front end of your site, make sure to use semantic code. By using descriptive tags to structure your pages, search engines will be able to read and have a better understanding of your content. This will also make the process of styling your site much easier and cleaner.
Use Meta Content and Meta Keywords
Use proper keywords and content relate to your web site, that helps search engine to crawl your web site.
Use unique page titles
Each page on your web site should have a title attribute, and each title should be unique. If you use the same title for every page, search engines will think that every page on your site is about the same subject.
Use SEO Friendly Page name or URL
The page name or URL must consist of the relevant keywords as it gives an idea of what the page is all about, Try to maintain a suitable length for the page name, The words in the URL must not be joined. Try to use hyphen between words in the page. The robots can easily index the URL’s with hyphens. Try to avoid using underscores.
Use Alt tags for Images
Specify alt tag for image and that alt tag should be a keyword related to web site, because images you have placed on site can be seen by visitors but not by search engines, so alt tag help search engines to read, with the help of alt tags search engines display the image results.
Use Heading Tags
Use your main targeted keywords in H1 or H2 tags. These robots give a lot of importance to H1 tags.
Use Valid HTML and CSS code
Validate your html and css code and make your code w3c standard.
validate your html code here
validate your css code here
Make your web site load fast
Don’t mess up your site with heavy images that makes your site heavy and slow, try to optimize images that reduces weight and helps to load fast.
Make a detailed sitemap
Make a detailed sitemap of a website. The search robots can easily go to any web page from this web page.
Use breadcrumb in a web page, if necessary. The breadcrumb must consist of relevant words reflecting the content of the corresponding page
Use Footer links
Footer link must be designed properly so that search engine robots can easily navigate through the web pages.
Avoid using Tables use DIVs
Try to avoid using tables. There are too many codes in tables and takes times to load page. Hence, try to use DIVs structure, which has less coding and takes less loading time. It has become highly search engine friendly because the robots can easily index it.