>>2308972>what's the best way to hold a figure when I need to pop something offThere isn't really a general way because of varying designs of joints.
>How firmly should I be grasping it, and where?Also depends on the design of the toy, but generally I would say, if you should hold close to the thing you are pulling off. If you're removing a hand, don't grip it at the chest.
>Should I just pull the hands\heads\whatever straight off, or use small back-and-forth twistsMost joints that I can think of, straight off, unless something is stuck or in the way. Back and forth twists break stuff, except with most revoltechs.
>Can most of this stuff only be learned through experience?Yes, although if you ask about specific toys or at least toylines, then we can help more.
>And as long as I'm asking, does anyone know how to get the Revoltech Gurren Lagann's chest piece off?See image. This would be a good instance to use the back and forth twisting since you can easily lose your grip by just pulling.