Here is a helpful pen and ink book, if you're looking for non-video resources for learning different mediums for drawing. Claudia Nice breaks pen and ink techniques down into manageable steps, helping you to develop a method of mark making so that you can communicate different textures and materials. Books like this are also great resources for learning when you're traveling and don't have an internet connection, as well as having paper images you can lay out in front of you while you're working. I like to have some on hand to loan to students. With the holidays around the corner, you might put this on your wish list.