You can secure your site by taking care of the following factors,
Access Restriction : Access should be reserved for trained and authorized technicians.
Network Monitoring : Regularly monitor the network for intrusions or unauthorized activity
SSL and Firewall
DDoS Prevention : Use proper tools to mitigate DDoS attacks.
Malware Detection and Removal : Regular file scans should be performed on client accounts
Password and User Access : The strongest passwords should be reserved for admin staff and guest authors since they have the most potential to impact the site.
Plugins, Applications, and Updates : When selecting plugins and applications for a website, consider their age, amount of installs and updates.
Backups : Backups should be automatic and frequent in order to maximize site uptime despite server failure.