As always, the starting point is to know where in Ireland your ancestors lived (and your cousins probably still live!). This is somewhat complicated by the Irish tendency to reuse the same name for places far apart (which many Australians have inherited). Mary showed us three of her favourite tools for getting a firm handle on names and places.
The presentation concluded with a brief discussion of (so-called) Land Records which actually contain much more material than the name suggests. Mary recommended that we become familiar with Valuation Office Revision Books and Estate and Manor Records that are becoming available online. A source like the Family Search Research Wiki can provide a good overview.