Symantec encourages all users and administrators to adhere to the following basic security best practices.

Use a firewall.

Block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.

Enforce a password policy.

Complex passwords make it difficult to access devices.

Sensitive files should also be protected with strong passwords.

Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task.

This helps to prevent or limit damage when a computer is compromised.

When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.

Disable AutoPlay.

To prevent the automatic launching of executable files on network shares and removable drives.

Turn off file sharing.

If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.

Turn off and remove unnecessary services.

By default, many operating systems install auxiliary services that are not critical. These services can be vectors for an attack. Removing these decreases your attack surface.

Always keep your patch levels up-to-date. 

Most importantly on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services, but ideally on all endpoints. 

Configure your email server to filter email attachments.

File attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files should be considered as candidates to block.

Train employees to be vigilant. 

Don't open attachments from any source unless they are expecting them or validate their authenticity.

Don't execute software that is downloaded from the Internet unless it has been scanned for viruses.

Don't visit questionable web sites. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.

If Bluetooth is not required for mobile devices, it should be turned off.

If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.

If you do suspect a device has been compromised, isolate it quickly to prevent threats from spreading further. Perform a forensic analysis and restore the computers using trusted media.

Technical Information
Disable Autorun registry key" enforcement in Windows