What is good to know about internet security in order to avoid being hacked and get viruses

You need to know what methods they use to try to breach your computer's security. The more common methods involve tricking you into giving away access, tricking you into installing malware on your own system, and taking advantage of vulnerabilities in your system.

 Hackers can trick you into giving up passwords by sending you fake emails (delivery confirmation, "account needs verification", etc.), pop-ups in web pages that look like system alerts.

 Some emails also come with attachments. If you aren't expecting an attachment, chances are it is malware. Double check with friends, go directly to your service websites, or disregard the mail entirely. There are also people that will call you, pretending to be a major software company and asking you to install software or give passwords. No company actually calls their customers like this.

Hackers also use expensive software as bait, offering "cracks" or "key generators" that are actually malware. The software itself can also be compromised directly. If any program is worth installing on your computer, it is worth buying a legitimate copy from a legitimate store, or looking for an 'open source' alternative.

 Keep your antivirus programs up to date, as well as programs like Adobe Reader or Java. (If you don't need Java, uninstall it.) Older versions of these software may allow malware to pass through, and potentially disable your security. Ad- and script-blocking extensions on your web browsers can block attacks via bad ads or bad websites.

Though not as common as before, flash drives and CDs/DVDs may carry worms that try to install themselves. You should disable AutoPlay on any Windows system, and make sure that your antivirus program is able to automatically scan removable drives.