*this post was written while tired, and so it rambles a lot, and I've had to edit it several times*
A lot of what keeps me involved and happy with a group is whether or not I feel like we are all on the same page. And as an Archmage, I've found that keeping up moral is very important for keeping my fellowships wanting to stay involved. You need to be clear about expectations, but also, you want them to seem less like expectations, and more like the goal everyone wants. Honey is sweeter than the whip, so if everyone feels like regular visits, tourney participation, ect, is mutually beneficial, and not just a demand, they'll stay happy and interested.
Decide what kind of fellowship you want, and build up from there. Specific rules can shift as you go along and learn more about what will best benefit your fellowship, but you should have your goals for the fellowship pre-decided. Nothing more distressing than when a leader up and decides to do a 180 with a groups direction. Whether you want something more active or laid back, decide what kind of place you want, decide on a few rules you think will help you achieve that kind of place, then refine those rules as you find the need. If you need to change something, be sure to explain why. If your members have the same goals as you, they'll be much happier to know that the fellowship is taking more steps in that direction.
People come and people go. Don’t get hung up by those who quit or move on. It may be sad to lose members, but in the end, think of fellowships as a place where likeminded people can gather. If someone moves on because they need more or less out of a fellowship, wish them well and keep moving on ahead.
Stay positive. People feed off of their leader’s mood. If a leader complains too much, or makes a big deal out of something, it can be very demoralizing to the group. On the flip-side, don’t take serious matters lightly. If something’s really bother a member or your group, too much forced positivity can be a big turnoff. They need to know you care about how they feel, and that you are there for them.
Delegate where needed. If you find you can’t handle running everything, find members who are willing and who enjoy doing a few tasks, such as tracking visits ect. While you need to manage and oversee your fellowship, giving members tasks and encouragement help them to feel more involved and part of the team.
And as Mykan said, celebrate achievements. If you’re trying to encourage tournament participation, get excited with each chest your fellowship unlocks, thank everyone for contributing, and research and explain the benefits of doing the tournaments. Even the small things need attention. If someone has been out due to life, and makes it back enough to put a few points toward the next chest, let them know you appreciate them taking time out of their hectic life to help out.
If you've led groups before, most of this will probably sound familiar to you. If you want to know specific methods and ways people keep track of everything, more than a few use spreadsheets, and I'm sure there's more than a few who will be happy to share. And what rules you set will depend on what you want out of the fellowship, which will go largely off of your own play style.