Hi Smitsan,
The interior should be painted some off white color, I have just checked new book I received today about Tiger tanks, and there are even some pictures of interior in middle stone or light panzer grey. The engine area same or brown-red often. You can find a lot online. I use Vallejo colors only to paint smal things, equipment etc., I have much better experience with Tamiya and Lifecolor paints, they are much more resistant. You must find out, what suits to you better, build and then paint, or to use painted parts for building. For me it is much more handy to paint some parts or together glued certain pieces and complete them then. Just find your way. And the last one, some chips, scratches, dirt, dust etc, to use for final appearance, whatever you would like to see on your model. I wish you good luck and hope to see your building here soon.
Libor
