Camouflage nets was used to some extent by the Germans during World War II, especially in the later half of the war, to prevent air detection. It might be interresting to use camouflage nets, either to create a nice atmosphere, or to cover up mistakes (this does not mean you should be sloppy in your work, though - to much camouflage will look unrealistic).
Verlinden Productions have some really nice pre-dyed scale camouflage nets, but this is expensive. You can acheive just as good result with regular gauze bandages, at a fraction of the price. One roll of these should last several years.
If you buy gauze bandages, they should be painted prior to application. I use normal water colors, painted on with a wide brush. This dries up fast, and since you will weather them along with the model, the base color is really not important. Khaki will be a good choice, though.
I like to put my camouflage nets on after the final paint coat, but before weathering. This resembles the real world the most (unless you want to weather the model, then apply the netting, and the weather again), and gives the best overall image of the model being an incorporated part. For glue, I use dilluted white glues - this makes the nets soft, so that you may shape it to the desired shape, and dries to up hard. This way, the netting will have a fixed shape, which will also keep the nets in place.
As said above, the nets should be weathered along with the model. Because the netting has not been exposed to so the same amout of wear and tear as the Panzer tself (usually), it should recieve lighter drybrushing, etc. than the model. Because the nets will look a little bare without it, I usually sprinkel on a little foilage (dried and grinded parsley - put it in the microwave oven a couple of minutes, as this will keep the green color, and prevent it from coming alove).
All contents written by Christian Ankerstjerne unless stated otherwise