nice info here - http://the-art-of-rouhollah-toghyani-blog.16451.n7.nabble.com/
basically instead of flooding a mesh with guides, as I've been doing, place guides with a little more thought & use it to drive the length of the "grow" & play with the influence radius.. Using a texture for the initial "scatter" density still seems to work well, although clean edge transitions still look a little patchy. I think using some maps to drive the opacity of these areas might help. ie, start to fade hairs as they approach the edge?
Crux of the link is - Use layers of hair - set A is a sparse distribution with correct lengths and overall shape. set B adds density and is clumped to set a. set C adds further density & some flyaways.
