One of the most common things I have seen over and over with friends and family computers is the lack of security for their computer. What I mean by this is that most if not all people have some type of antivirus protection but they lack one thing I have seen. What I have seen what most people lack is a firewall for their computer.
A firewall essentially is the gatekeeper which checks to see what information is being sent or what information is coming into the computer. This meaning if a would be hacker finds your IP address they can gain access.
Get a firewall for you computer.