Quote: "1. If that fence is going to restrict your player from venturing off where he shouldn't be, try and make it a wee bit higher so he can't actually jump that high. The transparent segments (I guess?) look bad if the player just bounces off it"
I have set the collision for the fence segments to 'box',this means the collision will come from the top of the support posts.
Quote: "2. Close to the edges of each plane for your trees, try and put in some transparency in between the leaves. Would look even more realistic for the tree."
As you can see from the image below,there is plenty of transparency in the trees,th transparency gets lost a little with the trees behind,tho' you can see it in any trees which are close.
I have still to place grass and shrubs and some low bushes etc,it all looks better in game.
In the screenshots above ther are around 50 trees so far,I reckon I could place many hundreds of these,they are only 8 faces each.Used back, front, left and right image planes making up the four views of each tree.