I began writing Undead Reckoning in January of 2013 (or possibly December of 2012). My idea was to write it serially, in weekly installments, with each installment being a kind of episode, like an old-time radio serial, or even like a TV series. Each installment would therefore setup a conflict to be subsequently resolved, or establish a character, and would typically end on a mini-cliffhanger; these installments soon became chapters, which explains the short-chapter format. As for planning, I intentionally kept that very light. At the beginning, I had only a vague notion of where I wanted to go with the story, so it began as an ambience piece, and evolved organically from there. My idea was that the characters were living this, and that they were reacting to the situations in which they found themselves, so to make it more realistic, I should do the same. I would put them into a scenario, and then figure out how they would get themselves out. It would have been a good "hand-off" writing project, and in some cases I envisioned it like that, imagining that I was setting up a conflict for another author to resolve.
Because I was writing it serially, and "reactively", I made a promise to myself that there be no planning ahead, and no editing behind. I stuck to that up until the story was finished, at which point I had to go back and edit for consistency and continuity. This was actually helped by my writing process along the way: as I was going, I kept copious notes about where people were and what resources they had, to help with the continuity. So the only real plan was: write a chapter per week, serially. Of course, plans are one thing, and reality is another. I mostly stuck to the plan with respect to how I would write it in installments, but as life intervened, the idea of one installment per week was not practicable. In some cases I went for weeks without adding anything, only to add a couple (or three, in one case) chapter installments. I still tried to keep to the general flow, and each chapter still could stand as an installment, I just happened to write them on the same weekend. I also maintained the discipline about not back-editing, which made it challenging sometimes.
I enjoyed the process of getting my characters into a situation, and leaving them there, and leaving myself with a problem to solve: how to get them out of their dilemma. Sometimes I got stuck, and it seemed to me that I had written myself into a corner, but always I managed to find a way out. This was perhaps the most frustrating aspect for my in-process readers (my eldest son and my wife), as they would read each installment after I had written it, and in some cases they would have to wait quite a while for a cliffhanger to resolve itself.
In the end, I believe it reads well, somewhat like binge-watching a TV series. I hope you enjoy reading it as much as I enjoyed writing it!