Short bio: Computer Scientist, FOSS supporter (read more)
Tux Machines (TM)-specific
Some time ago, the open source world was caught by surprise by the announcement of a malware for Linux, hidden in a screensaver for Gnome in gnome.look.org. Security in Linux (as with any operating system) is a matter of habit, then we will list some tips.
* Never work as root. Working with the root account is very risky. Use root only for maintenance tasks, with SU (or kdesu or Gksu), and never log into the system with this account. Browse the internet as root ? No way.
* Do not enable auto login if your computer can be used by others. Auto login is a very interesting feature, but if you have information you want to keep private, it is not a good policy to enable auto login.
* Be careful with Grub.