Okay, so these aren't really sketches in the true sense, these are the first stages in what will become something more like finished drawings.
I was planning to get back to some small oil paintings by this time in the summer, but every now and again I give in to the urge to work up some pencils. These are on a colored paper. It might be "canson" paper. I'm not sure (found a pad of it in my studio), but it does have some tooth to it.
The Steeler mini-helmet comes from a bank of compositions I set up for the oil painting version of the subject. Difference here being, an alternate background from the one in the oil painting.
Maybe these will have highlights placed with white pencil when they are done, and maybe they'll have a bit of color in the lights as well. Haven't decided yet.
Lastly, one great place I suggest you go for some inspiration on drawing, along with a few free podcasts, is Drawing Tutorials Online. That Matt guy really does it up right over there!