It all depends on your security needs. In other words, what you need in order to feel secure.
A few good browser extensions, as suggested, is important.
And don't forget to keep recent system image backups. Keep them on a media that is totally disconnected from your system, or else ransomware can encrypt your backups, too, even over a network connection.
Beyond that, you have to decide what level of security you want.
This could mean leaving things as they are, or adding an on-demand scanner, or going for more advanced programs such as VoodooShield and HitmanPro.Alert, etc.
It's in your hands.