Thank you, Jesse, that's exactly how I'm trying to proceed.
I learnt most of the script commands and the rest toying with a test location. Then I started making maps for my mod, and adding NPCs to them. The first town took the longest, of course, but it helped me master or at least "apprenticiate" the tools
Now map-making takes only half the time it used to and scripting goes 4-6 times faster than before.
My team isn't very big - I only work with my brother who takes care of most of the graphics side and helps me with the storyline, dialogue and NPC design. Thus we have very little problems with keeping our builds up to date.
Before we start a location, we have a complete, or at least 90% complete design document with all the necessary info - descriptions, map layouts, NPCs (with descriptions and tips on dialogue style), quests, etc. We also have a series of docs about general things in game, such as how the XP numbers progress, or how the equipment evolution progresses. There is a separate design document for the main quest and its elements, as well as changes to the world as the story unfolds.
Since we're only two, we avoid some of the cumbersome elements of modding, such as new critters, talking heads, loading screens, worldmap, movies, etc. Instead, we concentrate on the storyline and tying quests and NPCs together, since it were the different and complex relationships between the communities, organisations and single NPCs that we liked best in F2.
I hope we'll be able to finish one day. Keep your figers crossed!