I just open them carefully- I apply a little pulling pressure at first just to open the door from the magnet, then once that part is done, I open like normally, just taking some care, and I don't have problems with shaking. It's a case of getting what you pay for really - if you want something that's going to be stable when you open it you'll have to pay quite a bit more to find that. But honestly with just these tips I have no problems at all, it should work for anyone. It's like learning how to handle Hot Toys - if you handle them like a regular action figure they'll break - extra care is needed.
Cheers,
Ken