Neurolab was the last and most complex Life Sciences Spacelab mission flown. Neurolab, the third dedicated Life Sciences mission, included both human and non-human experiments and a greater variety of biospecimens and hardware than flown on any previous mission carrying Life Sciences experiments. Good science was accomplished, however unplanned engineering and operational events did occur. This paper addresses some of those issues, the pitfalls encountered in developing payloads for microgravity missions, and the lessons learned. It addresses hardware, biospecimen, and operational elements. It also suggests means of circumventing such issues as we progress towards development of payloads for the International Space Station. Recommendations are also made for pre- and post-flight processing.