Realistic Grass Effect

[Guest]

I saw in a video on Youtube that when applying grass you put a darker shade of grass on the terrain followed by a light shade on top.

I was wondering how everyone else applies grass?

Also, I have this gravel type material I bought (its black, 1kg for only $3 AUS which is a bargain!!!!!!!!) and if I apply a darker shade of green on top of the black gravel (and applying the same concept I mentioned above) would It look good?

Thanks!