The first key is prayer. This may sound almost trite considering we 'are' talking about churches and missions but I'm talking about prayer exercised in a real way. I have seen the altar flooded with men in Lima, OH and again in Paw Paw, MI which I believe God blessed in seeing these churches grow under their present leaders. I know prayer can be done anywhere but it just seems heaven may get a little closer when men humble themselves collectively at the front of the church.
Another act I liked was the month of prayer about Faith Promise Giving under Pastor Bickelhaupt in Oak Harbor, OH. He did not limit praying about what God would have you do in giving to just a week, but he passed out a 'prayer commitment' card in advance of his annual Missions Conference. Members were asked to pray about missions and, in particular, what God would have them do for a month before indicating on a given Sunday what the Lord had impressed upon their heart. Again, this was a growing church and a church that was able to add new missionaries on an annual basis.
One more church I learned from was Grace Baptist Church under Dennis White in North Ridgeville, OH. Along with prayer ahead of time he also planned a 2.5k day on the Saturday of the Mission Conference. The goal was to distribute gospel literature to 2500 homes. The end result was 2800 homes were given tracts with a church invitation and 5 first time visitors were recorded the next day (Sunday). Again, prayer was integral but "shoe leather" was added to push for a big day as part of reaching their Jerusalem with those reaching around the globe.
There are churches growing. There are churches adding missionaries to those they already support. Each has an emphasis on prayer, corporately and individually. All of these churches are doing so under the present economic conditions too. Just saying.