Look for a "lock" icon at the bottom of your browser and make sure "https" appears in front of the Web address before submitting any personal or financial information through a web site. These visual clues tell you the information you are sending is secure.
Verify links before clicking on them by hovering your mouse over the link and carefully checking that it's the website that you expect. The difference may be as simple as a .net address versus a .com address, or a slight difference in spelling, so pay close attention.
When possible, go to the source directly, and type in the company website yourself to verify and use the information from the website.