Playing with Charcoal and Pastels

I've never used Charcoal before and I'm still new to pastels. This weekend, I've been playing around with the two mediums. So far I like the effects that they create. What you do you think? Do you have any tips or feedback for me? :)

 Hyun Bin. Charcoal on paper.

 Yoon Doo Joon (Doesn't really look like him though :\ ). Soft Pastels on paper. 

Yong Jun Hyung. Soft Pastels and Marker on paper.