(Lincoln, NE, United States)
Sketching is a blast once you get good at it! Trust me, it's not as easy as it looks. Here's a tip that helped me a lot. Don't get discouraged. If you don't get it the first time through, it's okay. It took me a year or two to get it down.
Here's another good tip. Don't sketch too hard or else it won't look as natural. But if you sketch too lightly, then you won't be able to see it. (But if you are going to color over the sketch then do it softly.)
Don't use the very tip of your pencil. It will make the sketch look to dark. If you make a mistake, then don't just grab an eraser. Try to cover it with something or make it darker.
So now you know some things about sketching. Get out there and do it!