Protect the wp-admin directory:

This is the central part of WP website. To secure this use password protect where the owners submit two passwords for access- one for admin area and the other for the login page.

Use SSL to encrypt data:

Secure admin panel with SSL certificate implementation. This way the data transfer becomes secure between server and browser.

Add user accounts with care:

Multiple people access to admin panel increases security threats. Use plugins for users to make their passwords secure.

Change the admin username:

Admin as the username for administrator main account is easy-to-guess username so change this as soon as possible.

Monitor your files:

Use plugins like iThemes Security or Wordfence to monitor website file changes.