What is the best way to communicate with several federal agencies at once effectively?

I have to think of a way to find out the best method for communicating with several federal agencies in order to find out what works best. At my office, we%26#039;re trying to include several agencies in a new work program, and we want them to actively search out the program and find out how to use it. But I need to know what the best method to communicate with them would be. Anyone have any answers for me?