I don't know how helpful these are, as they may end up hurting, but I like to do forearm stretches. Heres the stretches I do (taken from http://www.handshb.com/2014/07/forearm-stretches.html ):
![](http://1.bp.blogspot.com/-wsMIGY1s7Ak/U_1VXjx2ghI/AAAAAAAAALk/m9d13Yq6rXU/s1600/Forearm%2BStretches.jpg)
As for breaks, I like to get up and move around, stretch a bit, and just generally do a self checkup. How am I feeling, do I need to use the bathroom, am I hungry, do I need to take a longer break, do I need to stop the class- things like that. I'm also trying to get into the habbit of drinking water on my breaks. Just remember not to push yourself too far- your health is more important than your drawing! Best of luck.