We're forever warning teenagers to be careful online – don't reveal personal information to strangers, avoid scams, report bullying behavior. The same advice may be appropriate for grandma and grandpa as well. Seniors are the fastest-growing segment of new Internet users, as they've discovered email, online shopping and banking, social networking, traveling planning and other online conveniences.

Even the most tech-savvy among us sometimes fall prey to online scammers, so if your parents or grandparents have recently taken the online plunge, here are some safety tips you can share:

Update security software. Make sure their computers have anti-virus and anti-spyware software and show them how to update it regularly.

Think like the bad guys. Even the best software isn't 100 percent foolproof, so teach them how to anticipate and ward off annoying – or criminal – behavior. For example:

Only open or download information from trusted sites to which you navigated yourself. Don't assume a link contained in an email, even from a friend, will necessarily take you to a company's legitimate website.

Don't click on pop-up windows or banners that appear when you're browsing a site.

Common email scams that target seniors include offers for discounted drugs and low-cost insurance, and supposed warnings from the IRS – which incidentally, never contacts taxpayers by email.

Financial institutions never email customers asking for verification of account or password information.

When shopping online, look for safety symbols such as a padlock icon in the browser's status bar, an "s" after "http" in the URL address, or the words "Secure Sockets Layer" (SSL) or "Transport Layer Security" (TLS). These are signs that the merchant is using a secure page for transmitting personal information.

These are all common tricks used to infect your computer with viruses or to install spyware that records your keystrokes to obtain account or other confidential information.

Use strong passwords. Believe it or not, the most frequently used password is "password." Other common, easy-to-crack passwords include simple numeric sequences and names of pets, spouses and children. For more secure passwords:

Use at least seven characters with a mixture of upper and lower-case letters, numbers and symbols.

Use unique passwords for each account in case one gets compromised.

Change passwords frequently.

Protect personal information. Never post sensitive information on any website (or share via email, mail or phone) unless you initiated the contact. This might include numbers for credit cards, bank accounts, Social Security, Medicare and driver's license, address/phone and full birthdate.

Set privacy controls. On social networking sites, carefully review privacy settings that let you limit who has access to your personal information. Similarly, always review a company's privacy policy to ensure you agree with how it may share your information with affiliate organizations.

Be skeptical of "free" anything. Before signing up for free trials, especially via pop-up windows or banner ads, make sure you understand all terms and conditions. Pay particular attention to pre-checked boxes in online offers before submitting payment card information for an order. Failing to un-check the boxes may bind you to contracts you don't want.

For more tips protecting personal and account information and preventing online fraud, visit www.VisaSecuritySense.com, which features tips on preventing fraud online, when traveling, at retail establishments and ATMs, deceptive marketing practices, and more.

Jason Alderman directs Visa's financial education programs. To Follow Jason Alderman on Twitter: www.twitter.com/PracticalMoney