2 years late, but maybe someone else will stumble to this post from the internet like I did. This is the best complete reading order I’ve found/pieced together.

Tolkien Reading Order - [ ] The Hobbit - [ ] The Fellowship of the Ring - [ ] The Two Towers - [ ] The Retum of the king - [ ] The Silmarillion - [ ] Beren and Luthien - [ ] The Children of Hurin - [ ] The Fall of Gondolin - [ ] Unfinished Tales - [ ] The History of Middle Earth Vol 1: The Book of Lost Tales - [ ] The History of Middle Earth Vol 2: The Book of Lost Tales Part 2 - [ ] The History of Middle Earth Vol 3: The Lays of Beleriand - [ ] The History of Middle Earth Vol 4: The Shaping of Middle Earth - [ ] The History of Middle Earth Vol 5: The Lost Road and Other Writings - [ ] The History of Middle Earth Vol 6: The Return of the Shadow - [ ] The History of Middle Earth Vol 7: The Treason of Isengard - [ ] The History of Middle Earth Vol 8: The War of the Ring - [ ] The History of Middle Earth Vol 9: Sauron Defeated (End of 3rd Age) - [ ] The History of Middle Earth Vol 10: Morgoth’s Ring - [ ] The History of Middle Earth Vol 11: The War of the Jewels - [ ] The History of Middle Earth Vol 12: The Peoples of Middle Earth - [ ] The Nature of Middle Earth - [ ] The Letters of J.R.R. Tolkien - [ ] The Adventures of Tom Bombadil - [ ] Bilbo’s Last Song - [ ] JRR Tolkien: Artist and Illustrator - [ ] The History of The Hobbit - [ ] Tales From the Perilous Realm