One thing most GMs will realize probably quite quickly is that you can’t really start a great campaign with “You are all meeting in a tavern” (unless you’re going for a pure treasure-hunting dungeon crawl, I suppose). Even if you have an overarching story in mind, it’s often difficult to slowly build up to the really big issues that will define the campaign. At first you get to kill some rats in the basement and then slowly work your way up until you eventually get to explore a goblin lair where the actual hook for the major part of the campaign will be found. And as easy as it sounds, it’s quite difficult to make it work well and be exciting and enjoyable for the players.
Fate presents an interesting take on this: Every new campaign should start with at least two big issues (though don’t overdo it or it gets too cluttered and confusing). These can either be current issues or impending issues. Impending issues are the things I just mentioned. The definitive story with a clear villain and a specific goal for the PCs. But something that seems to be usually overlooked in RPGs are the current issues. Instead of dropping the players into a world where everything is mostly fine until they run into the plot hook, you can (and I think should) also start the campaign with some kind of major conflict or other problem already in place. It’s something that is very common in fiction and in many videogames as well. Take for example, once again, Star Wars, where there is already dissent against the new public order and rebellion brewing in secrecy before Luke and Han get involved in the actual plot at all. It’s the background environment in which the specific adventure of delivering the Death Star plans and saving the princess takes place. It’s the context for what they do and makes that simple delivery run matter, even before they end up joining the rebellion and taking up the goal of defeating the Empire. The game Skyrim is also a good example. You get the Dragon storyline as an Impending Issue that slowly builds up during the first three or four hours of the game, but there is already the Stormcloak uprising against the Empire as the Current Issue, which has been going on for quite some time before the players character gets drawn into the story.
Now I really wish I had been thinking about this a week ago, so I could have made use of this simple method to start my new Castles & Crusades game, but with only the first session played so far, it should be easy enough to do this retroactively.