Make promises that can be kept. Build ownership on all levels. What a coalition can do Activity depends upon need, local assets and talent. The purpose should be to inform and mobilize voters. Education and activism are the two key words.
Some groups emphasize education over activism, or the other way around.
It depends upon how the group is set up. Many groups don't incorporate, although incorporation should definitely be considered. Try to get a lawyer pro bono. Visit Christian book stores to check bulletin boards and pick up free literature. Visit politically active churches.