I thought of just posting my sketch from yesterday, but the pic they posted was of young Spock, so I did a 20 minute warm up sketch this morning with my Kuretake No. 8 Fountain brush Pen.
Exercises like this help to stretch your artistic skill, and force you to draw things you might not draw otherwise. If your on Facebook look up the challenge and try to post on it a few times. You will be encouraged, and you will be challenged as you see how others all over the world are approaching the same reference.