I don't think installing antivirus could help you avoid phishing sites nor installing virus on your computer. It actually making it worse. After all, antivirus devs are the people to work on creating viruses in order for their business keep on track. Probably bookmarking, remembering the domain(.com, .org, .ph and etc), being aware on news about the exchange might help and secure yourself from phishing sites.
Why do you think so? Doesn't installing paid antivirus reduce the risk of virus threats?
When using the Windows operating system, I installed the Mcaffe Internet Security paid antivirus on my laptop. Proven to protect when surfing the internet, phishing websites are automatically blocked by the antivirus.