If you want to tidy the hairs around the edges of a face, then it can be a nightmare to do so with the healing tools. Instead, go to Filter > Liquify. Grab the Freeze Mask Tool from the toolbar and paint over the main bulk of the hair to lock it into place. Switch to the Forward Warp Tool, and use it to push the stray hairs in towards the face. Click OK and finish off by cloning any messy details along the edge.