By: kelbytv.com/photoshopkillertips/
Adjust the hardness and softness of your brush edges.
http://kelbytv.com/photoshopkillertips/2010/04/27/hardsoft-brush-edges/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+PhotoshopKillerTips+%28Photoshop+Killer+Tips+%28Video%29%29