4.) Don't give out your personal information. There's no reason to print your Social Security number on your checks, and most states allow you to use some other number for your drivers license. Never give anyone your social security number, credit card number, checking account number, or any other banking information over the phone unless you've initiated the call (this applies to catalog shopping as well). If you need to provide sensitive information online, make sure you're on a secure connection (look for "https://" in the address field). Never send that information in an email, and never EVER post any of it online -- not even your full address and telephone number or date of birth on your resume (once published online, it's public record and accessible by anyone).
5.) Monitor your credit card statements. Be sure to give the bill a once-over before you pay it, stash it, or destroy it. Unauthorized charges are easy to overlook, but could be early signs of identity theft. If a bill doesn't arrive when it's supposed to, contact the company right away; some identity thieves reroute your existing accounts to new addresses before opening new accounts using your information.
6.) Don't reply to emails from people you don't know asking for personal information. It's called "phishing," and it's a scam. If you hit "reply," even just to tell them to stop emailing you, you've confirmed that your email address is valid and left yourself open to more scam email offers. Also, beware of phone calls phishing for information, like the so-called "Jury Duty" scam (and others).
7.) Don't leave your bills in your mailbox. If you've left a bill there to be mailed, and someone other than the mail carrier takes it, you've just given away everything an identity thief needs to commit fraud using your name. Mail anything containing your personal information by dropping it into a secure post office drop box instead, or pay them online via a secure connection.
8.) Create hard-to-guess passwords. The more complex the password, the less likely someone else will be able to figure it out and access your account. Avoid using obvious or easily obtained information like the last four digits of your social security number, your phone number, your birth date, or your name. Whenever possible, use a mix of numbers, symbols, and both upper- and lower-case letters in your password or Personal Identification Number (PIN).
9.) Never take your Social Security card with you. There's no need to carry that little card anywhere, ever. Memorize the number, and leave the card at home. If the number appears on any other cards you use (a Medicare card, health insurance ID, or other membership card) scratch it out or obliterate it with a permanent marker.