http://ckgrs.com/index/TIPS_N_TRICKS.html
I had the good fortune to learn how to make trees for an indoor large scale train display. I have it posted on my web site for those who are interested. Regards, Dennis.
The ones we produce and sell don’t look quite as “wild”.
(http://www.easternmountainmodels.com/pics/EMM075.jpg)
(http://www.easternmountainmodels.com/pics/EMM072c.jpg)
(http://www.easternmountainmodels.com/pics/EMM072a.jpg)
We try to get the branches to grow out straight - even in Large Scale. 
The girl under the tree is Preiser 1:22.5
Thanks for the tips Dennis! I need to make a few for the portable layout.
Terry