Good antivirus. Don't download random emails with "unknow" attachment
Is it true that this virus is spread via email, what about security like yahoo and google? I am so scared .. 
I don't think that this particular virus spreads via email but many viruses do. For this reason, you shouldn't ever open unknown attachments via email.
This particular virus spreads without needing any user interaction as the vulnerability in Windows allows remote exploitation if not properly patched.