question?

First thing you need to do is define which type of tank you want to "destroy". Then you need to define the level of destruction. The more destruction you want, the better the references you are going to need. If for example you want to build one that is just burned out with a shot hole or two in the armour, then this is relatively straight forward. But if you want to show a catastrophic destruction of a tank or armoured vehicle, your references are going to have to show a complete interior to start with. As far as modelling techniques for doing this, once again it all goes back to what you want to build.

Here are some great examples:

http://www.missing-lynx.com/gallery/german/migpanthg.htm
http://www.missing-lynx.com/gallery/german/migpz3.htm
http://www.missing-lynx.com/gallery/german/mignuke.htm

Enjoy

This book may be what you need. That is if you can find it. Amazon shows it as 'not released yet'.

Super Detailing Techniques: Knockedout Vehicles and Heavyweights.
ISBN # 1902579674