David Troesch's 3 rules of staying safe on a computer
1. Keep all software patched and up to date.
Especially software that touches the internet. Why? This protects you from things automatically installing without any User prompt.
Your operating system updates: Windows Update/Mac Software update
Any software that touches the internet must be as up to date as possible
Web Browser: Chrome (preferred), Firefox (second), Internet Explorer or Safari (Last)
Programs that are launched from the web browser/internet
Uninstall Java if you don't need it (or are unsure). If it's installed, you have to ALWAYS keep it updated.
PDF reader (Adobe Reader especially - Set it to install automatically)
Adobe Flash in IE and Firefox (If it's available you're prompted to update when you reboot your computer)
2. Don't click/download install anything from the internet you didn't go out and specifically go and look for.
Why? This protects you from Phishing scams/social engineering tricks to trick you into installing something you shouldn't.
Never open an attachment in an E-mail.
If you break this rule, you need to be able to: Verify you are opening a data file (.doc, .xls, .txt etc. file) and not a program file (.exe, .vbs, .com etc. file)
Never click a web link in an E-mail
If you break this rule, you need to be able to: Identify the difference between what the URL looks like, and where it actually takes you when you click it. Use the popup or bottom left corner of the window to see where it's going to take you BEFORE you click.
Never open a program from your Web browser (Internet)
Program Install prompting for User name and password
Unless you know you're in the process of installing a safe program, the UAC (windows), or ID/Password prompt (Mac) is warning you to stop: The program creating this prompt will have the ability to do anything it wants to your computer, write/delete files, send E-mail's as you, collect your Windows Username and password.
3. Antivirus is your last line of defense.
You shouldn't need it unless you have broken either Rule 1 or 2. However if it's needed it will only catch between 80-95% of viruses. The 5-20% of viruses that it misses is usually the latest virus and the one you're clicking on right now.
You need to: Know what Anti-virus software you already have installed on your computer
You need to: Be able to identify if a program window is a window from a locally installed program, or a web browser window faked to look like a program window.Use the icon in the taskbar for the active window to tell what program it is.
And finally...if in doubt, call David. :-)