My adaptation of the Fudge rules are currently being reviewed by my players. So far I'm counting one very good sign. Each of the three players who have looked at the rules very closely have started telling me about the character they would like to create with the system. I take this as a good sign because it means that they aren't finding rules they hate or mechanics they can't stand. It also means they are getting even more invested in the campaign.
That gives me a lull in the world building and rules creation. So, I've been paying attention to adventures. Planning to improvise.
In my GURPS campaign I started the campaign with 1 person totally new to PnP RPGs and another who hadn't played in nearly a decade. To introduce roleplaying, I spent the first 2 sessions in an introductory adventure designed to teach the rules. In this campaign I don't think I need to spend that long introducing the rules because I have mostly veteran players. I'm planning one session for rules exploration. In this case, the rule teaching session will be a "friendly" competition to test the PC psi-marine squad against an existing mundane marine squad. The competition will take place aboard ship. The competition will include 3 contests to explore the 4 main rule sets; short range, single pilot, ship-to-ship combat; hand-to-hand combat; and a laser tag game that takes place on a deck of their home ship to simulate small arms combat. There will of course be some roleplaying opportunities during the competition and I've designed each test to allow for some psionic action so they can test their psionic skills during the competitions.
So where do I take the players after that? In my GURPS campaign, I tried leaving the world totally open. "Here's my world, pick a direction" I told my players. I think I was a little naive. It was my first time GMing. They followed a plot line, then when it got tough, they dropped it like a stone, went off on another direction, and by that time I decided to put them on a set of rails for a little while. I'm not looking to repeat my mistakes.
This time I've got my different factions and I'm looking to allow a little exploration of each faction but I've also got an overarching plot in mind to bring the players to explore the themes of the campaign: Loyalty, sacrifice, and the nature of a psionic identity.
The instructional competition mission mentioned above will include mid-level roleplaying but little fear of death. So, after that mission, I'm sending the PCs on a high adrenaline hostage recovery mission. I'm not always going to alternate like this back and forth between roleplaying and shoot-'em-up, but I want to show all the players early that there's something in the campaign for them. From there I'm going have a few missions that expose the players to some of the different factions in the galaxy. The majority of those missions have at least a small hint to a larger campaign arc (including those themes mentioned before).
What I'm doing is touring the campaign world (using the in game lever of military obedience to require the players to follow along). I'm also trawling the players for their interests. I know vaguely what the 3 major chapters of the campaign arc are but they can each be played out anywhere. I'll be waiting for the players to tell me where they want to play that arc out. Once they give me that sense, I bring them on the rails to the location they are interested in and set them free to play out their characters within the arc. That's the plan anyway.
So, how do I organize all this? I use the outline format in Word. Each roman numeral is an adventure. Some of the sub-sections are fleshed out, others less so. After each mission I look at the existing mission seeds and choose one mission to use two sessions ahead. After fleshing that session out I go back and look at the next session and see if I need to add any foreshadowing to that session. Here's another way of seeing this just in case this paragraph is confusing.
1. End one mission.
2. The next session is already planned and foreshadowed.
3. Choose a mission seed to expand and use two sessions ahead.
4. Review the preplanned session in #2 above and add foreshadowing for #3.
It creates a fairly seamless flow for a story arc and lets me improvise things within a session without being concerned that I'm messing things up down the road because I haven't built the road yet. And it doesn't leave everything totally open because I have these mission seeds percolating. When the players take a left turn I didn't plan, I can shove one of these percolating missions in their way with a few minor tweaks either to buy time to adapt or (if I think fast enough) I can adapt it to suit their purposes on the fly.