From this point, just keep adding hair curves along the scalp line on your model. Periodically up the display percentage on your hair to see what the full thickness of the strokes look like. This will save you time from doing a full blown render. Once you think things look good in the 3d viewport, to a full render occasionally to double check. In some instances, it may be necessary to add control curves to handle troublesome spots. Because the hair on my model was pulled back so tightly I needed to add curves above the ears to handle that particular patch:
Start off by open the hair_side_brush's tab tubes|creation adjust the tubes per Step, this will dramatically effect the speed of pfx renders and amount of hair you have. You don't need a lot actually, around 25 would be good enough.