Traceability

Ensure that any model, code or configuration changes are clearly recorded along with the recorded improvements (or degradation) that they produced. It is vital that you have a clear record of what was tried and tested and what yielded benefit. Most importantly it is vital that in the case of degradation it is easy to roll back and undo the changes made. Making and evaluating changes should be managed one at a time where time allows to avoid the possibility of an improvement hiding a degradation and vice versa.