Immortal Iron Fist:
Immortal Iron Fist #1-27, Annual #1
Immortal Iron Fist: Orson Randall and The Green Mist of Death #1
Immortal Iron Fist: Orson Randall and The Death Queen of California #1
The Seven Capital Cities of Heaven trade collects #8-14 and Annual #1 of the Immortal Iron Fist series by Matt Fraction, Ed Brubaker and Duane Swierczynski. This is really the definitive Iron Fist series, and the best jumping on point for readers new to Iron Fist. There's 27 issues, an annual, and two one-shot specials (Orson Randall and The Green Mist of Death and Orson Randall and The Death Queen of California). All of this is collected in the trade and the complete collections. You can also check it out on Comixology and Marvel Unlimited if you don't mind reading digitally.
Marvel Premiere/Iron Fist:
Marvel Premiere #15-25
Iron Fist #1-15
Marvel Team-Up#63-64
From the looks of things, the show will be heavily influenced by the original 11 issue Marvel Premiere run (Marvel Premiere #15-25) by Roy Thomas, Doug Moench, Len Wein, Tony Isabella, and Chris Claremont, as well as his first 15 issue solo run (Iron Fist #1-15) by Chris Claremont and John Byrn, that covers his origins and early career, and wraps up in Marvel Team-Up #63-64. All this is collected into the single Epic Collection: The Fury of Iron Fist trade, and you can also read it on Comixology and Marvel Unlimited.
There's more, like his team-up series with Luke Cage, his tenure with the Avengers and Defenders, and the more recent Living Weapon series, so hit me up if you want anymore recommendations and stuff.