I used to just create a story and try everything to get my players to run with it. I was basically doing a chaotic job of railroading and didn't realize it. My story development was mostly writing a story for a book and have the players fill in the blanks. Most of my players (7 out of 9) actually seem 100% ok with that, the notions of those other two, I dismised as unrealistic wishes. I took quite a brake from DMing, except for running a bit of City of the Spiderqueen, but that didn't have story creation on my part.
I'll be back to DMing soon and I decided to try and develope my own take on freer story creation. I want to try out two different, though similar, aproaches. The first will be used for an evil to vile PC's game that is thought as one-shot but will propably have some followups, the second is for my planned Iron Heroes Seafaring-Campaign.
1# THE MISSION STYLE:
This style brakes down the Story of every Session into three parts:
a) The Introduction
b) The Obstacles and the Setting
c) The Conclusion
This approach works only under the assumption that the PC's have a definite goal to fullfill every Session. In said one shot and maybe mini campaign, this is true because the PC's agents of an evil organization, that will have them eliminated if they fail at theyr missions.
In this style part a) and b) are more or less scripted events on the beginning and end of the session. The Intro describes the PC's, states their mission and propably starts the session with an inevadable fight with one of the groups from b). The Conclusion is, more or less some kind of Boss fight, an event that has to occur to acomplish the mission and also triggers the end of the session, with a read out text bringing thinks to a satisfiing end. the main part of the session is defined by two thinks: The Obstacles and Setting and how the PC's react to it.
For example the planned one-shot adventure:
a) The Pc's never met before, every players already knows the mission: To kidnap the Princess of a small kingdom. The adventure starts out with one PC viewing the Setting, the kingdoms capital, with the kings castle, from an elevated position (a roof or hilltop). The Setting's and PC's appearance are described. One after another the other five PC's arrive and are discribed. Between every new arival there's some time for the PC's that are allready there to interact. When everyone's there, robbers and zombies led by a nekromancer and an undead monstrosity attack the PC's, servants of the Council of Bones, the kingdoms prime criminal organization. A new obstacle and possible subplot is introduced, the PC's can show of their abilities.
b) The Setting is the kingdoms capital, it's general strukture is described, nothing more is definite and will be improvised.
The Obstacles are those parts of the Setting that oppose the PC's mission or their organization in generel. Most of these are the Settings power groups. Each has some generic NPC's and some more important NPC's prepared. These Obstacles are:
The city watch: It will make it hard for the PC's to enter and leave the city and do as they like.
The Royal guard and agents: protect the castle and Hunt down the kingdoms enemys.
The Sisterhood: order of monk/sorceresses that serve the kingdoms patron godess, protect holy sites and provide the princesses bodyguard
The patron godnesses Priestresses: protect holy sites
The Council of Bones: kingdoms primary criminal organization. The PC's may want to take revenge or meet more members if they try to enter the castle through the severs
The castle: Prevents the players from easily reaching the Princess
c) The battle vs the Princesses bodyguard, taking the princess prisoner or charming her, casting of a shadowwalk scroll, for as many PC's as possible to escape with the princess. Epiloque.
This aproach has very narrow uses, but should work out allright. It#s still very railroady, but has a reason to be. The missions accopmlishment defines the next missions goal. How the players reacted to the setting and obstacles, will define how it looks in the next mission that takes place there (in my example the PC's should be able to wipe out either the Council of Bones, the Sisterhood or the Priestresses and kill important royal agents)
2# THE FREE ADVENTURERS STYLE:
In this style the Players gain a primer for the campaign, that tells them the generel style expected of the PC's, the settings flavor and some major hooks of the setting, the players may use in charakter generation (for example there are 9 ancient worldwonders in my next setting, one of which hasn't been found yet, the PC's could be explorers that want to find the 9th wonder or see all wonders in their life). After characters are created and the campaign begann, I'll continually plant small plot hooks every session, some improvised some planned, in the form of mini adventures, rumors and NPC's. I'll continuall develope some of these, others will disappear again, depending on player interest and ideas, as well as my own. The major plot hooks will be developed as well of course and some of the small hooks may grow into new major hooks. I have no idea if and how this aproach will work out, but it will be interesting to see anyway.
Few, long post and propably not that interesting, but I hope you bear with me anyway.

If you've got tips or comments on this, they would be welcome. PM me, to not hike this thread. If there really is interest, or something to diskuss, I'll make a thread.