We take security of our sites (and our customers) seriously. Our primary focus is dealing with agencies of varying sizes on just about any of their technology needs but one of our specialties is securing and optimizing your WordPress site(s). At any given time we are working with WordPress sites across dozens of servers.
Here are some tips from our experience that are fairly easy to implement if you only have one or two sites.

• WordPress updates must be done in a controlled manner,monitored and verified.
• You need to have some sort of process to scan the sites daily, and someone to perform remediation on what they find.
• Perform daily scans against the WordPress repository for changed files. This is normally a sure sign that you have been infected.
• Offsite Backups, backups, and backups. Hopefully you see the importance of backups.
• Special .htaccess filtering and settings (these are can be server dependent and implemented in multiple ways depending on your situation)
• Blacklist monitoring for the server IP. If you are black listed
  If you are a little more technical
• Put all your sites on SMTP mail keep them off the server. There are any number of plugins that will do this.

For Further Reading

https://medium.com/@blakebhowe/securing-wordpress-sites-at-scale-519804a2f09d#.4s3koss11