Render him out using BEST RENDER in the RENDER panel with whatever light/material/shadow settings you need for your scene.
Once the scene is rendered go to the LAYERS panel and hit the BAKE button.
Now go over to the TOOL panel and locate the FIBER BRUSH from the popup menu
Now to see how NOT TO DO IT . Just draw a stroke across the head
without adjusting any settings. The result is a solid mass of dense hair that looks out of place.
To change the look of the FIBER brush hair there are a number things we
can do. First is to change the Material to FLAT.