Easy wins are reductions in energy use, and thus carbon footprint, that can be achieved with least difficulty. The ease of these actions is a subjective assessment, what is easy in one church or church hall or vicarage will not be for all.
Some suggested actions: draught excluders round doors, installing LED lights, using outdoor floodlights less, turning off the church heating 15 minutes before the end of a service, adding insulation to an accessible roof space such as a church hall, switching to the green electricity tariff, choosing low carbon travel options, modern remote heating controllers, avoiding long haul flights.