24. Failing to Lock Your Smartphone
When an unsavory type finds a lost phone, his first order of business is to call as many international and 900-type numbers that he humanly can. Then he harvests all the data on it for identity theft and spam purposes. Or you could, you know, prevent all of that by putting a simple PIN on the thing. You can find tools built to manage security for Android and other mobile operating systems.
25. Commenting Online
I know: You have the perfect bon mot to counter one of the points on this list, and you're going to enter it painstakingly into a Web form at the bottom of this article so you can be clever comment #86 on page four. Congratulations, sir or ma'am. Touché. Seriously, people, this is 2010. If you have something snarky or inflammatory to say, at least have the common courtesy to tweet it (politely).