Been a while since I looked at that tut, but my general method for well everything in photoshop is to just keep tinkering with brushes and colors and layers until it all looks good and I can't remember how to replicate the effect the next time I try it, LOL. In general my vegetation tends to b done with patterns (impressionist and non-impressionist often overlapping), soft round pressure brush with about 50% flow, with some bevel and texture effects. I tinkered with splatter brush but never really got into it. Another possible way to tinker with the color is to do a color overlay effect, that can help remedy a questionable color. So many toys in PS.
Also remember that sometimes, like myself grumbling at my first layer of mountains, that everything doesn't always look right until its further along.