Spine

What I've noticed about most cartoony 3d rigs is the torso doesnt move all that much when you rotate in a twisting motion. The only indication is you've moved the head, shoulders and arms. But what if you rotate all the joints and then counter rotate the top control back to default position? Then you've got yourself a hidden problem.

As with all counter rotation, translation or any animation, it's such an easy thing to do, but to keep yourself young and sane it's best to avoid at all costs. Remember what you've done and zero out as often as possible (except for the main rotation). This is also very important for any spine, shoulder or head controls that are translatable.

For example with a spine, most of my poses uses the rotate forwards and backwards axis. I usually try and keep any twisting or side to side bending to a minimum (that's not to say I dont use it, whatever is required for the pose should be used but remember it's there). When a character has positive and negative values on the same axis on various spine controls, but looks like it should be a relaxed default position. Clean it up! It's very easy and it's usually very quick to return the character to it's original pose but with a much cleaner, workable spine.

Rigging was my first job, and while I was very junior and have no idea how to script anything, I did learn from my lead, Oyvind Nostdal, how to keep a scene clean. While I have comitted all of the animation crimes above (and still do when I'm rushed or not paying attention), keeping an eye on these things have kept me sane.