Sharpie Sketches - Horses by ColossalBeltloop . I once heard an artist say that she liked to draw in pen because there was no erasing, and it helped her learn to accept imperfections. That seems like a good (albeit somewhat painful ) idea!
"How to Draw Hair tutorial by =ribkaDory on deviantART: by drawing the ends and hairs at hairline close together you can create shading and a sense of form. This will help if you are into drawing people.