Let's see, the process for my current (and first!) one shot has been like...
Planning
Like (presumably) most people, I spent a few months at the outset just like... writing/doing concept art/etc. For this project in particular I knew I wanted to hit ~50 pages (not super short but definitely not much longer than that), so I started brain storming something that could be told in roughly that limit. Bullet pointed major events, expanded on them in brief paragraphs, had to edit a lot of it down because it was getting way too long, etc. Character-wise, I didn't want to spend too much time on character design so I just grabbed some older OCs I had and updated them a little bit xD The antagonist and minor characters are all new though.
After editing the story down to roughly the right length, I went through and completely story board/thumbnailed the whole thing out over the course of a week in photoshop, using super quick crude drawings. I ended up overshooting my page limit some (I'm at ~60 pages) but it's close enough xD I did my script at this stage, since I find it easier to think of dialogue in the moment as I'm roughing the panels out rather than try to incorporate it into the "writing" phase. I had a few friends and acquaintances look this document over to give me some feedback before I moved on to the real pages. In particular one of the comments I got was SUPER HELPFUL and improved one of the main plot points quite a bit~
Actual Pages
I decided to do this project with traditional line work and digital coloring, so my process starts with pencils on 11x17 paper. I've been buying some brand that has non-photo blue comic margins on it to help ease the layouts a little bit. gives me an outerborder to work from and base my parallel lines off of and such. I mostly reference the storyboard that I created for each panel as far as the general layout goes, but some panels do get shifted around and such. For example, now that I've been working, I've found that I was a little too generous with how many panels per page I had allotted, maybe only two or three. In some of those cases I steal panels from the following page to make the page a little more robust or end on a stronger note (I'm doing mostly page-by-page updates).
Inking I do with mostly my dip pen (g-nib) and pentel pocket brush pen. I still use fine liners for the panel borders and such though~
Then I scan the page and do some basic clean up in Photoshop. Having PS around is helpful with my traditional line work because if I make a mistake I don't have to worry about applying whiteout or anything, I just just fix it digitally xD I also occasionally move things around a smidge (I recently had a panel where the lone figure was accidentally tilted to the right... so I rotated her back to the left lol).
Coloring I do the basic flats -> multiply layer shade -> effects/highlights type method. I'm super new to digital art in general so this has been the biggest learning curve for me, figuring out how to do things both better and more efficiently xD been getting a little better every page though, I think.
Lastly I do my speech bubbles and lettering digitally on top of everything else.
I work in batches of 3 pages typically, sometimes +/- 1 or 2.