When you learn Irish, the goal is to become perfectly fluent. Not Gaeilge bhriste, but Gaeilge chliste. The very idea of reviving the Irish language is about reviving it as an authentic language. This means that you are supposed to have as good a command of it as an average Irish intellectual would have in an alternative reality where Ireland still was an Irish-speaking nation. For this, you will need to re-enact the personal linguistic development of that alternative-reality person. This might sound scary, but it is actually easier than for many threatened languages, because in Irish there is a wealth of folklore and native autobiographies available. In fact, the reading list I published here can only scratch the surface.
If you were born in an Irish-speaking Ireland, the first things you’d learn in the language would be children’s folklore. There is a lot of this stuff available in the folklore collections. Other folklore is to be recommended too.
There is another reason why I speak so much about folklore as a source of good Irish. In a community where literacy in the native language is unknown, but where there is a thriving oral culture of storytelling, the storyteller and the tradition-bearer is the best equivalent to the writer and author in a literary society. The best native writers of Irish were born to stpryteller familias. Thus, if you want to learn the kind of Irish that was appreciated by the last monolingual native speakers as the best traditional Irish, you mut learn the storytellers’ Irish. This is also why Peig used to be taught to learners. She was the daughter of a storytelling family, and a renowned storyteller and tradition-keeper herself.
Now of course somebody will start kvetching about how Peig, or Gaeltacht literature in general, has nothing in common with modern life. I beg to differ. I have translated Isaac Asimov into Irish, I have written popular science in Irish. The language I needed for writing popular science I learnt reading folklore and native writers. I did need to look up the terms in specialist dictionaries, yes. But the rest, the system of the language, came from the folklore.
That folklore is the literature of the last custodians of the traditional language, the Gaeltacht people. As a student and learner of the language, you are their servant, you are the caretaker of their heritage. Myself, I am but a servant of theirs.