My Top 5 Computer Tips:
1. Have installation media kept handy. That way, if worst comes to worst, you can perform a re-install. Optical medias, are a dying form. Personally I still use them out of habbit. The only reason they've survived this long is because music is still widely sold on CD, and movies are still widely sold on DVDs. Flash drives are the future, but I'd suggest using an SD/SDHC/SDXC memory card in a bootable usb card reader instead. This will give the you the same benefits of having a flashdrive installer, but you'll also be able to take advantage of the card's ability to disable writes by flicking the "write" tab to read only.
2. Create a backup of your OS, and of your data. Put some thought into the types of backups.
3. Install a good firewall application. Preferably, one that blocks anything you've not made an exception for. At the very least, run a firewall application.
4. Disconnect from networks when you're not using them, especially if you get internet access through them. Hackers can't hack your computer unless they're connected to it. Personally I don't do this, but I still recommend doing so.
5. Have 2 accounts. One for administrating the system, and one for using the system.
Haven't made my signature yet.