When using a website for research, be cautious. Keep in mind that the majority of the information you find online goes through little or no review process. Start out by reading their "About" or similarly titled pages. Always consider the organization and their purpose behind the site:
Think about possible conflicts of interest between the site owners and the information included. Be especially wary of sites with lots of advertising. Look for research credentials and contact information, ideally an e-mail address, phone number, and physical address. They should cite their sources just as you would in a research paper.