The basics for protection against ransomware is :
- Update frequently (OS, AntiVirus, ...)
- Don't open phishing / infected emails which usually convey the ransomware (user awareness)
- Backup, backup, backup (and check them!)
The majority of the ransomware risk is cancelled by a proper backup strategy. If your data are safe in some offline place, they can crypt whatever they want. It's surely a hindrance to go through the restore procedure, but it does not cost more.
Some basic techniques might also help, email filters, macros scanning/disabling, using a least privilege policy for your user.