If you don't have a basic knowledge about internet security like dangerous website that host malware and spyware or phishing site you can rely on this internet browser add on extension from McAfee called Site Advisor. This extension will notify you the security rating for every website that was display in search result by search engine line Google in small icons.

There are four type of rating that will show by Site Advisor, here is the rating and the represented icon :

You can see the rating icon in search result like example below:

To declare the rating for each sites, McAfee did some test called "Automated Web Safety Testing" that based on E-mail Test, Download Test, Online Affiliation and Annoyances Test. This test result also can be view in Site Advisor website when you request a report by submit any domain name in  "View a site report" form. You also can view other Site Advisor registered user review comments in that report. So, based on this report, Site Advisor will declare a security rating.

This extension only supported Internet Explore and Mozilla Firefox and you can download it here.