Ask yourself these questions when you come across a website. The 5 W's will help you determine the reliability and accuracy of a website.
Who: is it a business, school, government agency or something else?
What: is it a blog, wiki, advertisement, article, or something else?
When: When was the website last updated. Try and find the copyright information on the page you are viewing.
Where: is the web address a .edu, .com, .org, .gov or something else. This will help determine who created the site.
Why: Is the website for entertainment use, to persuade you or inform you?