In May of 1932, then New York Governor Franklin Delano Roosevelt (running for President in a Great Depression era) called for "Bold, Persistent, Experimentation" in dealing with the failing U.S. economy.
I love the phrase already! Bold. Persistent. Experimentation. I think it would be a great church mission statement. Bold proclamation and presentation of the Gospel in a clear, relevant, and holistic way. Persistent evangelism, though with humility and incredulous love, and persistent discipleship not relenting until the transformation into Christlikeness is substantial; and persistence in fulfilling the Great Commandment and Great Commission; frankly, persistent in everything - taking so seriously that the harvest is plentiful but the workers are few and that the local church is the hope of the world! Experimentation is such a great way to describe the humility it takes to try new ministry endeavors. Don't announce you are going to try this new such and such program for here on out; announce everything as a (bold, persistent) "Experiment"! Then when you experiment for bold, persistent effectiveness you can evaluate and adjust because you've given yourself an 'out' because it was just an experiment.
Above all, it seems that "Bold, Persistent, Experimentation" is an ideal motto for Church Planting!