I have been thinking about adding some foliage as camouflage to my Flames of War models (once I have finished painting them). Looking at photographs of real tanks, such as the Canadian Sherman Tank in Italy above, there is certainly no one way to do this.
One consideration when modelling in 15mm, is that though the true reason for adding foliage is to camouflage the tank. I do think you can add too much foliage, which may be authentic and realistic in real life, may look “weird” on a 15mm model. It may look like a moving bush or tree, rather than a tank with added foliage camouflage. Part of that reason is that in real life the tank when stationary needs to appear to be hidden, but once moving it would be obvious it was a vehicle with foliage on it. In 15mm the models do not move by their own power, so it can look “weird”.
So next question, how do you model foliage on your 15mm models?