How Do You Write Your Campaigns/Adventures?

[DanDare2050]

For D&D type games I map using a hex grid of 10 mile hexes. Plonk in some sparse civilisation. Name the biggest bosses. Then the biggest monster bosses "out there". I write an index in word and give each boss some agenda. I look for obvious conflicts.
I never stat. I use the monster manual as is, don't even roll hp, and some web pages that have lots of NPC stats.
On a sheet of paper I lay out the powers and draw a network web. Then I chuck some clues (3 clue rule) so on a normal campaign map that's about 30 clues. Usually just two or three word short hands.
Story Cubes : GM's best friend. Roll them a few times to generate an idea about the three most important things going on, overlaid over what has been put in place.
Random encounter tables : a universal one and then maybe some by terrain type and if I'm feeling really grand some special location ones. They should be things to encounter that can just jazz things up or connect to something already in place when they are chosen. My tables always enclude "projection" as an element, that means find something keyed nearby and have an encounter with something related to it, even if its just "you see a green dragon flying about 5 miles away".
That is way enough to get started.

Each session I use character creation and player driven things to connect players to things going on. Sometimes players muse about something and then its "yeah, that is exactly what is in the world". Anyone here played Technoir? I use its mechanism to create lots of NPC / player connections during play. More story cube rolls to handle quick back stories for random monsters and npcs encountered.

As detail expands I start breaking my word doc index into regional chunks for easy access. It also gets notes added during play.
I constantly type session notes as I GM. Its become a habit and I have learned to type, talk and improvise all at the same time. Later I go through the notes and further update my database. After about 6 months of a campaign I rework the notes, and chuck in changes to the plots and agendas, unless the players have already forced that which they usually do.

Oh and I have a stack of 5 room dungeons as "ready rooms" with three free floating clues about each of them. I will randomly chuck a clue to one in the players path. If they bite, or bite at a 2nd or 3rd clue later, the dungeon becomes fixed in place somewhere and the players may assault it or avoid it as they see fit. The dungeon denizens may become a local force or regional factor if left alone or if they remain active after the players leave.

Oh yeah, as Mark mentioned above, callendar times when things go off unless disturbed. Worked great for the build up of an orc army after the players had released some ancient orc king spirits, that eventually possessed some dwarves, who then went and started rebuilding the "great orcish kingdom". Also, patrol rosters in dungeons etc, always handy for a dynamic setting.