[Shostak]

Originally Posted by FF_Ninja

• A functional understanding of whatever digital tabletop environment I want to use - leaning towards FoundryVTT presently. That'll take time.

• This should probably be your lowest priority, and you might not need to invest too much time in this. I use Roll20 for games I GM, and I play in some on Fantasy Grounds. I keep the R20 tabletop VERY SIMPLE, using few of the bells and whistles that make an RPG game played on a VTT seem more like a videogame than a tabletop experience. Fog-of-War and all that stuff is nifty, but not anything I want to have to deal with, and my players haven't complained. You can draw your own simple maps w/Roll20, or--even simpler--draw your own simple maps on paper and import jpegs of them to use as your maps. This works for me, because most of the substance of our games doesn't require tactical maps.
  
  

  A decently fleshed-out world in which I can run a campaign. Even if I start "big" and flesh out broad details, I'm not even sure where to start. And I want to be able to take a bite out of this one so badly, it's been escaping me for years.

  Start with an adventure you want to run and create that. Then think about what implications it presents, jot those down, and build out from there.
  

  At least a passable knowledge of whatever books I want to use.

  Yes. But you don't necessarily need everything from each of the books.
  

  Assets. Digital tabletop makes things a lot easier, but I'm still going to need to generate assets (maps, splats, etc).

  Roll20 gives you some assets for free, but I made my own counters from my PDFs of The Fantasy Trip and Cardboard Heroes. Easy and no extra money.
  

  Recruitment. It'll take time to attract and vet players.

Just start with one adventure and let things grow from there.

I'm confronted with this mountain. I don't want to put it off any longer, nor abandon it because it's "too big."

I just don't know what to do right now. I want to take the time I have and use it fruitfully.

Once something is started, it is easier to keep it moving. I've occasionally organized cartooning sessions for the museum I work with, and a strategy common among the artists is to have a lot of paper and to just make a few lines on a page and let a drawing emerge from them--an S shape turns into a dragon, or a zig-zag turns into a running person. To use this for writing, just write down a list of words that come to mind as you think of your adventure or world. The words don't have to be sentences--just one word per line. You can use the single words from your list to build sentences that describe your adventure, and then whatever parts of your game world you need to support the current adventure. And then, just repeat as you need for further adventures in the same world or to create a new world.

Good luck!