I dropped out of school when I was obsessed enough with Max and render engines, spending 12-14 hours a day just testing every area. After some time I started getting contacts via the forums where I had posted my renderings to share with others.
My "secret" tool is Vray2SidedMtl. It's a cool way to create realistic leaves for vegetation and, in my opinion, it's better and also faster for rendering than using translucence map.
The key for photorealistic vegetation, besides correct tools, is understanding how it behaves, what it does, what it smells like.
Analyze distance to vegetation on your render and real necessity for detailed materials - this way you shorten rendering time.