Plexiglas - Can be installed inside on existing windows. This also endures a great deal of force. Ensure lights are not accessible to normal reach. Security cages placed over the lights will ensure they are not turned off or broken. Privacy vs Security - Crooks love to work in the dark.
Shadows provide cover.
Alarms - Do your homework on companies. Ask people who have alarms. Get a minimum of three quotes. Registering with the False Alarm Reduction Program is required. The police may get your property back and will need some form of identification to return it to you.