Guidelines for evaluating websites.
Purpose
Authority
Timeliness
Scope
In Google, you can limit your searches to specific websites, or you can focus your search efforts on specific types of websites
To limit results to a specific website: [search terms site:apa.org]
Example [Obesity site:apa.org]
To limit results to government websites: [search terms site:.gov]
Example [Arthritis site:.gov]
Google also has an Advanced Search page that you can use to exercise more control over your searches.