If you are looking for design and content guidelines you should follow to make a quality site with nothing wrong with its design and content quality then you must have a look at following guidelines specified by Google itself.
1- Use Transparent Hierarchy and Text Links
Use transparent hierarchy and text links while designing the site. At least one static link must be there for every page. Design the site map as a convenient guide that user find beneficial in finding important links in your site. If the site map has numerous links try and break it up into many pages. Keep considerable number of links in a page.
2- Use Informational Content
Use informational content that is accurate and useful for the users. Guess the most commonly used words, which users invariably end up using while searching through the net. It would be highly recommended if you can actually incorporate these words in your pages.
3- Use Text or Add Proper Text in ‘Alt’ Attribute of Image
Use text and not images to suggest important names, links or content. Google crawlers are unable to recognize texts contained inside images. If use of images is unavoidable then using ALT is recommended to help you include texts describing the content along with the image.
4- Remove Broken Links Immediately
Both your < title> element and ALT attributes should be exact and illustrative. Broken links must be detected as earliest as possible and correct HTML. Not all search engine spiders are able to crawl dynamic pages so if you intend to make a dynamic page keep this in mind. This allows the search engine to keep the number of parameters short and restrict its numbers.
So don’t forget these design and content guidelines while going to create quality sites for you.