To get you started quickly you can download these two materials, one uses thinSSS for the most realistic looking grass, the other uses the same textures but no thinSSS for fastest rendering:
This material uses two Layers, the top Layer has a Layer opacity mask set to use UV channel 1 to give some variation in color over the grass surface. See the Grass page in the documentation section for more info.
The randomness of the natural grass is achieved
by using high Variation percentages for Length,
Angle and Bend.
To get the characteristic golf green look
(very dense, short, but also chaotic), a strong and
homogeneous Cut Off is important and a large
Initial Angle Variation setting.
On such a short grass, the Flat primitive works
fine and renders faster.
For a less perfect golf green, set Cut Off to 100% (which
means the full length of the blades will be rendered) and
increase the Length Variation.
Tall big grass
Even for large bendy blades of grass, with enough
Points per Blade, the Flat primitive looks perfectly
smooth, and renders faster than the Curve primitive.
The large height of this grass needs a larger Bend Radius
to make the blades bend slowly over a large radius.
Fast Generic Grass for housing projects
On projects where the grass is not the focus,
you can save a lot of Ram and render time by
optimizing the grass distribution with the Level of
Detail settings, depending on the size of your scene
and what the camera sees.