a lovely diorama so far mate!!
as alan says there are some things that could turn it into a super diorama!! the fences are a good idea and buidling some mud/dirt whatever around the tanks tracks is a good idea as well.
do you own an airbrush? if so, try shading the grass with different tones of green and maybe some brown patches where the grass has worn thin?
i tried that kind of effect for the first time. take a look here;
http://www.scale-models.co.uk/showth...hlight=netting
i used the games workshop "grass" there as alan also suggests.
let us know what you think. cant wait to see it progress!