Yep, having the right equipment is a must, thought I've heard of some pretty scary attempts to do it without the right stuff.
For ergonomics the two things I've noticed most often at our Community College are students actually trying to stroke the rods with their wrists intsead of their arms and excessive stone pressure. The most common problem is high stone pressure, once those rods get going they just don't want to stop, which puts a real strain on the arms when you're trying to reverse their direction.