Need some advice on settling with car insurance?

My car was stolen from my driveway, the car was located the next day in a pond. Front body damage, smashed window glass, front tires flat, the front half was submerged but not completely over the engine and up to the cup holders inside. There is water in the oil and the gas cap was off so something probably happened there. The flat tires were completely bald so I am sure there is clutch damage. The insurance company is coming to get it and take it to a savage yard for assessment of the damages. Either it's totaled or not but either way I am sure I will not get what it's worth, it's their business to make money. What can I do to be prepared? How do they determine the value? The car had upgraded stereo, exhaust, tint, iPod adapter, etc… All electronic equipment was stolen. It's a 2000 Honda Civic EX coupe in excellent condition. Thanks for any help you can give.