It's a handsome beast. Here are a few points I picked out. It may just be that I can't see the model very well, I have a small screen, but I thought I caught a hint of unpainted plastic down the inside of the muzzle. This would have been black if the gun had been fired lately, and the outside of the muzzle would have been coated in black powder residue. A good way to replicate this is with black pastel chalk. If the gun has not been fired recently, the barrel would be a gunmetal color and the paint on the muzzle would be slightly darker than the rest of the paint.
The edges of the road wheels were steel so they would be a bright shiny metal color, or coated in bright orange rust depending on the last time driven. The tracks would be dark brown rust overall with shiny metal on wear areas or bright orange rust on the wear areas, depending on how long it has been since being driven. Bright orange rust can develop in less than a day if not worn off.
The ring on which the machine gun sits would also have the paint worn off by swinging the gun around, so it would also be a shiny metal.
You might want to figure out if it has been raining in your diorama any time recently. If it has the tank would be coated in mud with liberal amounts throughout the running gear. If it hasn't, the tank would have some dust on it, also depending on usage. A long hard ride down a dirt road would coat it in a thick layer of dust, which would be blown or worn off if the tank has sat for a while. Either way, there should be some remnants of dried mud on the lower hull and on the road wheels.
There will be a few spots where the crew normally moves over the vehicle, so hard edges will be worn in varying degrees through the primer and possibly down to metal. Again, judgement should be used to denote either metal or rust. Also, flat paint has a tendency to get compressed when rubbed on, so where the crew walks, take a pencil eraser and rub in a few spots to simulate this.
And finally, metal rusts, so all the little fittings all over the tank would be prime targets to show a little rust on. These would be perfectly shown with rust colored pastel chalks, as these should be more subtle. Not all would be rusted, and all would show varying degrees of rust. Also, rain and gravity would cause the rust to drain down the vertical surfaces of the vehicle, so use subtle streaking down from the fittings you choos the rust.
Your Konigstiger is looking pretty good and has the makings of a well done kit.
Rob