Basically to keep interest up, we limit the number of times we play a year. At the start of the year (january), we have an informal meeting at a friends house to plan dates. We go threw and pick and eliminate dates that work for most people. Then we send out a mass message via any means possible to potential players we want playing. Tell them to invite one or two friends they feel would be fun to play with (not necessarily good, but FUN!). We don't want idiots/jerk faces out there ruining it for everyone. Plan plan plan ahead. People can look forward to it a lot more when they have a good idea of when they are actually going to play. Don't say, "hey guys, in two weeks we are going to go play paintball." You aren't going to get a lot of people since it doesn't give much notice.