In general I've been avoiding drawing challenges because I'm feeling really inspired in all my project. However, I couldn't resist partaking in the "Friday Face" challenge by the Sktchy app.
I really enjoy the community on the sktchy app. Since this challenge is free and only once a week I figured it'd be fun to play the challenge with the artists there. The way it works is every Friday you're emailed a reference photo and an art-making tip provided by another member of the community. I wouldn't have ever picked the reference photos myself and that's part of the fun!