If you can’t identify Irish origins, by researching the family in North America (or wherever), then switch to the branch of your family who went elsewhere. How do you prepare for this? The assumption is that all siblings were born in the same Irish parish. So to find the birthplace of one is to identify them all!
I suggest you obtain a good genealogical how-to book. These will identify the records for you, and help you to understand research strategies. For example, if you’re researching the branch which went to the USA, the standard general how-to books are: The Source: A Guidebook to American Genealogy (3rd ed. 2006), edited by Loretto Dennis Szucs and Sandra Hargreaves Luebking; and Val D. Greenwood’s The Researcher’s Guide to American Genealogy (3rd ed. 2000). If you are researching in the UK, with an emphasis on England, you won’t go wrong with Mark Herber’s Ancestral Trails: The Complete Guide to British Genealogy and Family History (2nd ed. 2006). These are but examples.
Also consult the website of the local genealogical society for their recommendations. For example, on the Ontario Genealogical Society website: www.ogs.on.ca you will see they sell Brenda Dougall Merriman’s Genealogy in Ontario: Searching the Records (4th ed. 2008) which is a VERY good book. The same principle can apply to the Society of Australian Genealogists: www.sag.org.au which under their bookstore category “How To Books” you will find an excellent selection of texts.
Another option for identifying how-to works is organizations and companies which sell or publish books. Examples range from Genealogical Publishing Company: www.genealogical.com in the USA to Global Genealogy: http://globalgenealogy.com in Canada.
The last option I want to share is online guides which you can print out. These are typically found on a genealogical society or archive website. I consult these all the time when I need information. Some online guides are general in nature while others are record specific.
All of these are methods I use to identify reference books. As a professional genealogist, I also have questions which need answered. Nobody knows everything about genealogy. This is where a solid how-to book is a wise investment.