After the bones are positioned, you must determine the best rotation order for each one. Do this with care.  Body part joints consist of three seperate joint primitives, one twist and two joints.  The twist primitive is always placed on the first rotation.  Because of ordered rotation problems, it is best to place the most likely rotation angle last with the remaining rotation angle placed in the middle.  For example, a shin should twist in Y and is most likely to bend in X; the best rotation order is therefore YZX.

Poser determines the probably optimum rotation order for each bone created with the Bone tool.

Select rotation orders by opening the Joint Editor palette and selecting the desired rotation order using the Joint Order menu.  Changing a joint order will probably require you to readjust the bone's joint zones as well.

You can also opt to use curve bends instead of the twist/joint/joint rotation order described above.  Body parts set up in this way have one twist and one curve.  The curve automatically bends the body part as if that part belonged to a chain of curved objects.  This feature is useful for body parts such as tails or antennae.