Make sure windows is completely up-to-date and patched using Windows Update. Sometimes you may even need to run Windows Update 2-3 times to get it fully updated.
Update Browser, Flash, Java, Adobe Reader
Your web browser, Adobe Flash, Java, and Adobe Reader are the 4 most common things that are exploited/vulnerable on windows computers. It is extremely important that you have the latest version of all 4 of these.
Now that your browser and all its plugins are updated, You should now install Adblock Plus.
Adblock Plus: https://adblockplus.org
Right after you are done installing Adblock Plus, A new window should have came up saying Adblock Plus has been installed. There will be 3 extra features on this page that you can enable for Adblock Plus. I would suggest enabling them all. You want to switch Malware Blocking, Remove Social Media Buttons, and Disable Tracking all from the off position to the on position.
Proper Virus and Malware Protection
Having your operating system, browser, plugins, and software all up-to-date is not enough. You should have a good Virus detection software running as well of a spyware/malware scanner installed.
Free AntiVirus Programs
Panda Cloud – http://www.cloudantivirus.com/en/
Avira – http://www.avira.com/en/avira-free-antivirus
Microsoft Security Essentials – http://windows.microsoft.com/en-us/windows/security-essentials-download
Avast – http://www.avast.com/en-us/index
AVG – http://free.avg.com/us-en/homepage
I prefer the first two free ones the best. I always have had the best luck with Avira and Panda Cloud. Obviously you should only choose and install ONE of these.
Paid AntiVirus Programs
Eset Nod32 – http://www.eset.com/us/home/products/antivirus/
Kaspersky – http://usa.kaspersky.com/products-services/home-computer-security/anti-virus/
Bitdefender – http://www.bitdefender.com/solutions/antivirus.html
F-Secure – https://www.f-secure.com/en_US/web/home_us/anti-virus
I would probably choose Kaspersky at this point in time, but I honestly don’t think you could go wrong with any of these four. Again, you should only choose and install ONE of these.
I would also suggest installing at least one anti-malware program also. I prefer MalwareBytes along with Hitman Pro.
User Account Control and BitLocker
User Account Control can be annoying, but it is actually pretty useful for controlling changes made to your computer, preventing anything you did not authorize. I would suggest making sure this is enabled and either on medium or high setting.
Encrypting your hard drive(s) may also be a good idea for your PC’s security. There are many great 3rd party applications that do this, as well as a built in function called BitLocker with newer Windows Professional and Enterprise versions. While this will help you beef up your security, it may also slow down your computer causing higher disk I/O and put slightly more strain on your CPU, so use with caution.
I wouldn’t bother with a software firewall anymore because most people use routers which has a firewall built in. Also, windows firewall is fairly decent which should be enabled by default in most Windows installations XP or newer.
You may also want to check out two other browser addons called Ghostery and NoScript. NoScript is amazing at what it does, but can be annoying sometimes as it breaks some sites functinality.
Ghostery – https://www.ghostery.com/en/download
NoScript – https://noscript.net/
Encrypting your internet traffic and hiding your IP addresss online may also be a good idea. It’s hard for someone to attack you online if they don’t know your real IP. Say some bad guys are trying to DDOS you or something, you simply disconnect from VPN or change IP’s/Locations on the VPN and the attack has stopped. For this, I suggest using https://www.privateinternetaccess.com
If you ever need to run a program or open a file that is kind of sketchy and you aren’t sure if it has something malicious included in it, you should run it in a sandbox or a virtual machine. That way, if it is a malicious virus, it won’t infect your computer.