With most of my work linked, some tales more closely than others, this page is designed to advise as to the suggested reading order.
Accursed - Underbelly - Eidolon - these three books form a trilogy. These stories tell the story of James Grey, a spiritualist medium and soldier, from World War II through to the Cold War. The only complication here is that Laura Spencer, the female lead from Accursed, is an immortal witch and she features in earlier tales in a supporting role. That being said, I still think this trilogy is the best starting point.
Oblivion - this book is set in 1899 and is another potential starting point to new readers. The old magician and leader of the Pagan Resistance from Accursed, Georges Steil, features as the lead character here. This is a short book (140 printed pages) and my personal favourite, a mad dash against time featuring my favourite and most endearing character, a foolish jester with his heart in the right place. There are several sequels to this tale, all featuring Georges, which go in the sequence of Toys for the Dead - Black Lodge - The Hydra Effect - Heretic Apocalypse - Beyond Salvage - Fallen Idols. Toys for the Dead and The Hydra Effect feature characters that bear grudges based on the events of Oblivion so I would recommend reading Oblivion prior to starting these tales. Although almost 40 years separate the two tales, Black Lodge and Fallen Idols are closely connected. All of these novellas are collected in Cults, Curses & Cryptids, which also features the short stories Unsuitable and Waiting For War, which are preludes to Heretic Apocalypse and Fallen Idols respectively.
Death Transitions complicates the above, being composed of three novellas featuring Georges Steil. The reason these stories have been collected together is that they feature shared themes of the fluidity of identity and the impermanence of death. The three tales are The Black Moth, The Cleansing of Cecily Carlisle and A Temporary Death.
Family of Prey is another novella featuring Georges Steil that deals with the Poirier clan introduced in Black Lodge. Cold Summer Love is a short story featuring the same characters as does Pagan Resistance: Marseille.
Revived - this 21 part series is set in 1652 and doesn't feature any of the characters from the other stories or at least not prominently so my only advice with this series is to read it in order.
Traveler's Respite - this 5 part series (also available as one file) is not connected to the other books (though a connection is being developed) and is a homage to the classic Hammer Horror films and portmanteau films of the 60s and 70s. There is now a sequel, The Dusk Mistress
Gifts from the Gallows and The Second Circle are two novellas that don't feature any supernatural activity. Blair Leigh is the lead in both tales, a private investigator introduced briefly in The Cleansing of Cecily Carlisle - there's no need to read that novella first as Blair's appearance is fleeting. These tales are me trying something different outside of my comfort zone.
Enlivened, like Traveler's Respite, is another supernatural tale of linked short stories, this time set in a hotel during World War II. No firm link to the majority of my other books as yet though it is set in the same world.
I wrote these books and I'm confused reading the above so hopefully this timeline of when the books are set may help.
1652 - Revived
1880s (unspecified) - Traveler's Respite, The Dusk Mistress
1899 - Oblivion
1900 - Toys for the Dead
1906 - Black Lodge
1908 - Family of Prey
1909 - The Black Moth
1914 - The Cleansing of Cecily Carlisle
1916 - Gifts from the Gallows
1918 - The Hydra Effect
1919 - The Second Circle
1924 - Unsuitable
1925 - A Temporary Death
1926 - Heretic Apocalypse
1929 - Cold Summer Love
1934 - Beyond Salvage
1940 - Waiting for War
1943 - Fallen Idols
1943 - Pagan Resistance: Marseille
1943 - Enlivened
1944 - Accursed
1945 - Underbelly
1947 - Eidolon