Don't download programs from sites you don't trust.
Don't visit sites like
http://archiveservertwoplustwo.myawesomescamesite.zk and enter your 2+2 login details.
I shouldn't need to say this, but apparently the latest 2+2 hackings were partly delivered via "chess" downloads. That's what the current announcement is about.
If you are interested in securing your computer against malicious attacks, start with the stickies in the
Computer Technical Help forum.