In Poser it is essential that the first order of rotation be axial to the body part. The order of the other two is less important but it has been suggested that the direction in which the body part bends most should be last. This means that a humanoid figure in the 'T' pose will have a rotation order of YZX or YXZ for the torso and legs whilst the arms will have a rotation order of XYZ or XZY. The foot is possibly a special case since its twisting is done primarily in the lower shin so should be YZX.

As mentioned above there are a number of on line tutorials available. My on screen video tutorials may be found at:-

http://www.philc.net/rigging1.php
http://www.philc.net/joint_parameters_1.php

Hope that helps.