1. Backup your data! We all know we should do it but how many of us actually do? Helpful hint, make them automatic.
2. Install antivirus software. Something is almost always better than nothing but be wary of free softwares that often package add-on's and even adware in the download files. Some of these work well, but do your research first or choose one of the well know brands. Tip, the average user doesn't usually need a full security "suite."
3. Take out the trash. The last time I checked there was 12GB worth of files and data sitting in my trash can. Oops! Wasted space. Periodically take the extra two seconds to click "empty trash."
4. Turn it off. If you are having an issue with a program, try turning off your computer and waiting 5 seconds before turning it on again. But don't forget to save what you were working on first!
5. Use passwords. With everything we use our computers for these days (banking, work, etc.) it's more important than ever to protect this information with a secure password. That means not using "password" or something as obvious as your name or birthday as the security code. And while you're at it, don't forget to password protect your wifi.