Since I've had a lot of people ask me how I outline using filters in photoshop, here is a tutorial on how I do it. Some extra notes:
*Since we changed the mode to grayscale, you will need to change it out of grayscale in order to color the image when you are done.
*Instead of Levels, you can also use Curves in order to make your lights lighter and your darks darker. This is usually if you have a lot of light lines on your pencil scan that you want to remove.
Next time I'll post how I color the image. Thanks for looking!