Always make sure your operating system is updated to the latest version. When vulnerabilities are exposed within the operating system (such as Windows Vista or Windows XP) software companies such as Microsoft release patches to close the hole. Its important to set your operating system and security software to update patches automatically, that way you can be sure your computer has the latest security protection.
Use effective anti-virus & anti-spyware software to protect your self against.
A personal firewall will stop uninvited users from trying to accessing your computer. A personal firewall will alert you if any spyware already installed on your computer is sending information out.
You should only ever download software from websites you know and trust. There has been a huge increase in the number of bogus software products. Quite often you believe you are downloading a harmless piece of software, when actually you are installing a piece of malicious spyware. If your children use a computer, make sure you talk to to them about the potential dangers of free software. You should always read the EULA (End User License Agreement) before installing any software on your computer. If you cannot find thr EULA or it is unclear, think twice about downloading the software.