The fundamental piece of knowledge required in researching Irish relatives is to know the exact Townland that they originated from. In the absence of postal addresses the collection of fields that made up a specific Townland provides the basis for further research. For example, in Cloone Parish the Griffiths Land Registry entries of about 1857 lists 3 pages of Moran's in various Townlands in Cloone.
Regards,
John