Not sure how beneficial this thread will be, as the show seems to be going in a completely different direction than the books did. This isn't The Walking Dead, where the plot is mostly the same, just with some characters swapped around.
As it stands right now, the show is basically expanding on Jesse Custer's five years in Anneville (which the books completely skipped over) while merging it with the "Meatman" aspect of the "Salvation" storyline. Which makes sense, because the Salvation storyline would've never went over well as a TV adaptation. For starters, Tulip and Cassidy are completely absent from that story, and you can't do that on a TV show. You can't just tell two main characters "ok, we don't need you this season, go and find something else to do, and we'll see you next year."
So I guess we'll be getting more into the idea of Jesse Custer as an actual preacher, which we only got in one single issue in the comics, and how he deals with his crisis of faith and being lured into the adventurous and freedom that Tulip and Cassidy both offers. They also seem to be beefing up the roles of Fiore and DeBlanc, and having them sort of assume the role that the Featherstone and Hoover had in the books.
While the comics immediately hit the ground running, introducing the Heaven / Hell schism, the origin of Gensis, and the Saint of Killers in the first issue, I think the show is going for a more gradual approach. We'll start with Jesse Custer and Anneville, then gradually open up his world. I expect to see Grandma / Jody / T.C. and that whole back story in the second season (and possibly Cassidy and Tulip's back stories as well), then we'll get to the Grail and the conspiracy to bring around Armageddon in the third season, and then it'll ramp up from there on.