I've decided that I'd like to dedicate some time to writing my own version of a Irish pagan-inspired theogony. I plan on dedicating some time to researching some Hellenic and Indian theogonies in order to gain a broader understanding of Indo-European beliefs, as well as more thoroughly engaging with the Book of Invasions in order to determine which elements seem vital and which might not be necessary (like perhaps Noah's flood). I'm interested in making a story that best reflects my own religious understanding of beginnings, endings, and the nature of the universe. I'm not necessarily trying to make an incredibly detailed myth, but at least something that covers the broader strokes. And I'm not trying to retell the Book of Invasions or necessarily expand on it. I'm just trying to make something that is "True" to me.
That said: does anyone have any advice about things I might want to check out? Like anyone else who may have tried something similar (I had a book of Celtic myths once where somebody tried something like this, but after reading more source material, I'm not very satisfied with it)? Or other sources that might help me refine my philosophy? If anyone has any other Celtic sources (perhaps from the Welsh) or artifacts (like from the continental Celts) that shine any light on these issues, I'd be interested in those too. Or any published articles that might shine some light on the issue would be interesting as well.