Google has released a general guideline for SEO (search engine optimization). User, who interests in SEO, may download the PDF and have a look.
For references –
Google’s Search Engine Optimization Starter Guide
Google’s SEO Starter Guide: https://webmasters.googleblog.com/2008/11/googles-seo-starter-guide.html
Guide in English:: https://www.google.com/webmasters/docs/search-engine-optimization-starter-guide.pdf
Guide in Chinese: https://static.googleusercontent.com/media/g.hi18.cn/en/us/intl/zh-tw/webmasters/docs/search-engine-optimization-starter-guide-zh-tw.pdf
Google Webmaster Tools
http://www.google.com/webmasters/tools
Webmaster Guidelines
https://support.google.com/webmasters/answer/35769
