Another is when in doubt add more space between the fragile object and the outside of the box. One of the most effective ways to do that is called double boxing. The inner box surrounds the object with material that conforms to the shape of the object and prevents or minimizes movement. Cushioning is provided between the inner and outer boxes/containers/crates - whatever. The most common mistake at this point is the making poor choices about the type and especially the amount of cushioning used (usually a foam). I almost always see beginners using too much foam with the result being more shock transmitted from the outside of the package to the object when it encounters an impact.
I put a diagram here https://app.box.com/s/4xzbheoq63l6tmuw4kpy