These tips are based on my experience with the development of QueryHome and it is 1st one in the series:
As search engine is the cheapest way to reach your customer so you like to design the website from that angle and the first is the structure of URL.
1. Us descriptive word in place of short word in URL.
2. Avoid special characters in URL and use "-" in place of underscore.
3. Keep URL depth till level 2 i.e. www.mydomain.com/abc/abcd
4. Keep the URL structure in the following priority
www.mydomain.com/123/why-do-birds-sing (This is the best what google/bing likes)
www.mydomain.com/?qa=123/why-do-birds-sing (This is the worst among above)
5. Use same domain in place of subdomain if possile i.e.
www.mydomain.com/subdomain (use it)
subdomain.mydomain.com (avoid it)
Important Header HTML Elements
Define Title Tag as follows and keep the title about 50-60 characters.
<title>Technical Social Network - QueryHome</title>
Define the Meta Description about the webpage and keep it between 110-160 characters
<meta name="description" content="Technical Questions and Answers Site for Technical Collaboration and Technical Networking.">
Search Engines these days does not read the keyword so you can avoid the keyword meta tag.
HTTP Status Codes
Use the following commonly used status code which tells the search engines about the existence of the page or error on the page.
200 - Success
301 - Moved Permanently
302 - Temporary Redirect
404 - Not Found
410 - Gone (No Longer Available)
500 - Internal Server Error
503 - Service Unavailable
Above should suffice however look at http://en.wikipedia.org/wiki/List_of_HTTP_status_codes for more codes.
In case you have more then one page with the similar or duplicate content then guide the search engine with the preferred URL to be indexed and avoid the search engine penalty.
<link rel="canonical" href="http://tech.queryhome.com" />
more to follow...