Avoiding phishing scams is tough. Phishers know every trick in the book, and they're dreaming up new ones as we speak. So here are some things to keep in mind while you're online:

Don't believe every warning you read — especially pop-up warnings that appear while you're surfing the Web. Unscrupulous companies use pop-up ads to display false warnings about your computer. Ignore them.

Do NOT click any button in these pop-ups, such as a "Close" or "No" button, or the "Close" box that may appear in the upper-right corner of the pop-up. Doing this might install a virus or other malicious software on your computer. To safely close a pop-up ad, press Ctrl-W (if you're using a Windows computer) or Command-W (on a Mac computer). You may receive an email that claims to be from a computer expert, warning you of a virus. These are usually hoaxes. Do not follow the steps described in any email unless you're sure the threat is real.

There is no Yahoo!Xtra Lottery. Don't be fooled by people pretending to be from Yahoo!Xtra and offering cash prizes. We would never send you information about a contest you never entered. If you've received a message like "Final Notification: Yahoo! Mail Winner!" or "Your Email Address Has Won $XX million," it's a scam. Don't reply to the email, don't click any links in it, and never divulge any personal information. Instead, click the "Spam" button.