Secure the computer by turning on Windows Firewall under Control Panel.
Learn more about each setting and what it means on Microsoft's website
Do not use your Administrator account as your primary account. You can find this account in the Control Panel under User Accounts. Save this for when you install software. This way if a virus does get through, it won't corrupt your personal files. For this reason, it is important to keep your personal files on your Standard User Account.
Install 3rdparty virus and hacking protection like Norton 360. One important thing to remember here is to not to install free programs because in order to keep them free, they often modify your settings to allow pop ups and ads to be displayed thus, compromising your security if you clicked on them. Sometimes things that are free, are not just as good especially when it comes to your private information.
Install a VPN client on your computer to use when you need to keep information secret.