I don't have a picture handy

I don't have a picture handy at the moment. If im using plastic windows from tichy for example i just glue the clear styrene to the window after it has been painted and then use a sharp fresh exacto blade to carve a broken window pane.

Also if i want a building that you cant easily see into i coat the rear of the pane with white glue. it distorts the view so you cant see a non detailed interior.

One Tip I Heard

Was to drill through the glass using a #80 drill bit to simulate either a rock or bullet, then create spiderweb cracks away from the glass using a sharp X-acto blade.

Another idea,

is use that thin plastic that covers some medicine packaging. It's easy to break up and then glue in window opening, my.

Broken window

This N scale wagon is a derelict lurking in the long grass in a far corner of the yard. It originally carried Pintsch gas - used for carriage and station lighting a hundred years ago. The windows are 5 thou clear styrene painted a dirty white and cut to the desired shapes before gluing inside the wagon.

Tony in Gisborne, Australia

Actually, if you use glass microscope slide covers.........

.........you will inevitably have actual broken glass that looks very real. (it's very easy to break while cutting it!)  It also breaks realistically after being installed.   Cutting plastic allows the viewer to see how thick (way over scale) the "glass" is.

Tons of this product is easily available, see below:

https://www.google.com/search?q=microscopr+cover+glass&ie=utf-8&oe=utf-8#q=microscope+cover+glass&*

Peter

Broken windows

Thanks y'all. Some very good tips out there. 

Glass chnaged in time

Don't forget that glass used to be simple panes, then safety glass came later.

The look of broken glass varies depending on the era you're modeling.

Just a thought, if you use

Just a thought, if you use real glass try placing clear tape on the back of the piece, cover the front with a cloth or thin cardboard then carefully hit the cardboard and break the glass. The tape should hold the pieces together so you can install it as a unit. Maybe apply a thin layer of clear adhesive on the outside surface around the cracks to insure a sturdy assembly. 

S