I'm a big believer in the theory that every great idea can only be greater by starting organized. So, here's what I do to keep myself (and my girls) together.
Every few months, I update our schedule and get a copy to each girl to have at home. The leader before me would take out fliers each week as a reminder. While effective, it wasn't such a great use of my time (having two kids of my own). I really felt like the time I was spending making and passing out fliers could have been spent more wisely (be it preparing for activities, playing with my kids, etc.)
I've found that giving the girls the information and keeping them accountable for their own attendance has totally resulted in more girls every week. I make sure to visit their classroom on the Sunday I am passing the new schedules out so that I can personally put one in each of their hands. The girls that aren't at church get a visit at home. I'm a big believer in enabling kids to be responsible and trusting them to make good decisions. By giving them the information they need and letting them know I'm counting on them to remember, our attendance has gone through the roof. They even bring friends because they can plan ahead and know what activity we're doing (not the specifics, but an idea).
I, too, keep one handy (on our fridge) so that at a quick glance I know what we're doing for that week. It totally helps with prep work (if needed) and also is a great record for anyone that might take the calling over after me. I keep each in my binder as a running list of activities we've done as a group.
This document, combined with my attendance roster, totally keeps me organized with goal setting for each girl. And, the girls love coming up with ideas based on upcoming activities. It's totally made for a well-oiled and much participated in activity days group.
Hope it helps!