Full Idea
There are some 'principles of selection' in abduction: 1) prefer simple explanations, 2) prefer coherent explanations (consistent with what is already held true), 3) prefer theories that make testable predictions, and 4) be comprehensive in scope.
Clarification
'Abduction' is inference to the best explanation
Gist of Idea
Abduction aims at simplicity, testability, coherence and comprehensiveness
Source
J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §2.01)
Book Reference
Baggini,J and Fosl,P.S.: 'The Philosopher's Toolkit' [Blackwells 2003], p.38
A Reaction
Note that these are desirable, but not necessary (pace Ockham and Ayer). I cannot think of anything to add to the list, so I will adopt it. Abduction is the key to rationality.