Thank you a lot, but I still think that the rest of the community can drop their 2 CP here on tips of how to do this.
Oh of course, I just wanted to share what I had.
As for extra tips, what my group loves is rolling their own random loot on random loot tables, so a lot of the time when they go shopping I let them roll through the loot tables to see what they find in shops.
@ Luna: I too am not stuck trying to finalize and flesh out a unique town for a base in a campaign :)
I find the whole town for me usually hinges on what makes it unique or fantastic. I'm designing a large town called Inderwick and was struggling with it for days. Then I looked at where I'd placed it: at the mouth of two rivers where they then disperse out into wooded bogs. Two major forests also hem in the town which is what give it the "insular" quality. Finally I was reminded by a player in an unrelated email that the backstory to my homebrew involved the Wilding; a period of roughly 80 years when the wilds of the lands were affected by magic and grew and spread insanely.
I had my hook. One section of the town is completely engulfed in forest and swamp territory. The townsfolk are working to reclaim the area but many of the buildings intertwined among the wilds have now become lairs for monsters plus there's worse yet just roaming around in there.
Locals call it the Gnarl. There is a mercenary group that has become an organization in town called the Lantern Watch. Originally they were hired to supplement the town guard at iron mines delved under the peat but since the Wilding they've reclaimed a small manor on the verge of the Gnarl, crafted a section of wall connecting it to the eastern gate of the town and are now sort of the "Harpers" types for Inderwick, patrolling the Gnarl and holding the new wall.
Building towns can be a HUGE time sink if your adventurers aren't going to "play" in town. I learned that the hard way when I made a village of 350 souls, and had names, class and level for every last one, full stat blocks for those with PC class levels, notes on behavior, rumors, etc etc etc.
Then the party sold the junk they looted from the goblins and heading back into the wilderness. About 5 minutes of play time.
Fortunately, I still have that village and all those NPCs, and I can mix and match them at need. I already used Hamm Ironarm, and they're going to another smith? They haven't met "Silky" Ana Posder, and there's no need for them to know what she was originally statted up as an assassin. In fact, they tend to get more engaged with the character when the name is not as pathetically suitable for the roll as Hamm Ironarm the smith.
@ Ny: I concurr. That's another reason I like the Gnarl; its a built in megadungeon to make the party stay in town.
Adventure 1: party happens to all be in the market at the same time it's attacked by a brute and a rat swarm. PCs deal with the attack after which a Lantern Watch agent shows up; he invites them to a party. At the party he asks them to go on an expedition in the Gnarl - interlude to a modified version of Master of the Fallen Fortress.
Adventure 2: when the PCs were at the party in the last adventure they learned of some vicious rats in town, a bit about a missing debutante and a band of thieves. If they don't actively pursue one of these hooks the Lantern Watch agent will ask them to look into the rats. Any of these hooks will lead them to a spooky mansion in the north wards, along the river.
Adventure 3: the PCs will have had the opportunity in the last adventure to obtain several clues and will have faced off against 2 of the three hooks intertwined with one another. While trying to gather info/process the clues or what not, a noble family in town invites them to yet another party. While there the party, taking place in the nobles' private cemetery, is attacked by undead. A trip to the crypt is in order where fey have invaded the crypt and created a little dungeon on the fly.
Adventure 4: the clues and info needed from adventure 2 come together. Either the PCs should have it figured out or they will be told that one of the 3 potential antagonists from adv 2 (ratfolk rogues, dire rats or a thawn) escaped into the Gnarl and that several pretty young girls have seemingly gone missing. At the same time there have been more brute attacks. Following any of these facts will inevitably lead the party in to Gnarl a second time on the trail of an adept wererat named Shara Mooncrazed.
Adventure 5: having fought your way through down one path or another to the fey-haunted copse where Shara has been you find her missing. However a gang of thawns has kidnapped your Lantern Watch buddy while you've been away. You head into the sewers beneath the town to rescue him.
Adventure 6: the PCs have had enough cat-and-mouse. They got to physically see Shara last adventure but lost her in one of the battles. Now its time to take the battle to her. There will have been clues along the way however, from her father's empassioned plea to spare her in a previous adventure to the fact that kids she turned into rats in adventure 2 were actually her tormentors, that lead you to believe she may just be misguided, not evil. This deduction is not needed to end the adventure but can grant an XP boon if they instead offer Shara a chance at redemption before destruction.
So...tips and tricks right? Well, here's 1 tip that goes w/what Ny said above: figure out what the PCs are going to use the town for.
If you don't know, or if the party will be using the town for little more than a campsite, then create small, detail little. That way if their interests change for some reason you can always add more later.
If however you intend the place to be a focal point of adventure, then design the features your characters will need. Are you using optional training rules for advancement? If so - provide training facilities. Is the PC cleric RP'd as a hardcore zealot? If so SOME kind of religious institution is in order.
As described above, I like to give the place a hook; some reason for the PCs to care about THIS settlement above others. As demographics go, even a scattered low-settlement region should have a village every 5 miles. In that sense if you have a 30 mile hex you determined to be settled, it could conceivably have 36 villages and towns scattered around it. Why then, as the party crosses through an endless sea of disgruntled serfs, rolling fields and rural churches, should the place you wrote up matter?
Griffons watching over the town from the surrounding hills? An active volcano under the Cathedral of Asmodeus? A wizard's tower forever enshrouded by purple thunderheads? Any of these and more.