Windows 8 is fairly secure, however, it does have many flaws.
I think a start then, would be to not allow Remote Assistance and not allow Remote Desktop Connections, always have to enter a password to get into the Desktop, and general sense. Some of the common sense things to do for Windows 8 is to not download questionable apps in the Windows Store (only download from trusted providers), don't roam the internet without antivirus & firewall, keep User Account Control on, and don't click on questionable links.