Preparing and running stories tailored to the other characters is just one way of contributing to the saga. There are also vis sources to detail, places to describe, etc. So you can look at the maps () and decide to lay a claim on a specific place and develop it. This will come, of course, with some stories that could happen there. The same can be with people.
As the Alpha storyguide, I am the final resource to balance things out. So if some specific reward and impact of some event is too much (or not enough), I will discuss with you ways to bring it in line with the power level of the saga.
That doesn't mean I need to know all of the details. I want to play in some stories as well, so some things can be kept secret. But establishing with me the broad outline of an area, or people, before fully developping it help keep things safe. Some things can be simply discussed with the troupe.
Let's take an example. As part of the background of the covenant, there was an arragment reached with the Telsberg family head by Leonardus for the use the small valley. Since Leonardus is gone, Clusius will have to go meet the Telsberg to present himself as Leonardus' heir. Since this is a story that my magus will need to be heavily involved in, I asked if one of the players was interested in developping the Telsberg family based on some thoughts I had on the subject. Houlio offered to do that, and also prepared his own companion to be from the Telsberg. So he has a "claim" on the Telsberg family, as indicated in this Notes and Claims post.
So there are plenty of opportunities around if you want to work on something while you complete your character! Take a look at the maps, take a look at the proposed vis sources. Share your ideas for stories, interesting locales or people. Tugurium is a place where Leonardus gathered people that didn't fit well in medieval society, so some of them, while not "playing" material, can add color to the saga. After all, the steward isn't even alive (note to self, finalize Julius' character sheet). 
As a final note, many of the posts in The Covenant of Tugurium, Grogs and Covenfolk, as well as Notes and Claims are set up as wikis, so that anyone can edit them. So when you create a new character, or a new place, you can just add them in the right place and create links. If you have trouble doing it, don't hesitate to ask!