Check out this site for examples of the damage you seek to inflict on your beautiful Tiger:
http://www.battlefield.ru/destroyed/german.html
As far as actually replicating the damage, it depends if you want the hit to be penetrating or not. If yes, then use a soldering iron or something similar to create the indented impact. For the holes in the shrouds, try using a drill bit and then make the edges a little more jagged with the sharp point of a hobby knife.
(note: I've never used either of these techniques myself and strongly recommend trying them out on a sheet of scrap plastic or old model kit before attempting on your completed item).