A key element of successful proposal preparation is establishing a relationship with your sponsor early in the process. The purpose of the initial contact with your funding agency is to confirm the common areas of interest of the sponsor and the PI/PD. A contact at the funding agency can also facilitate proposal preparation, serve as a resource for answering questions, and shepherd the proposal through the agency's review process.
The What to Say–and Not Say–to Program Officers article in The Chronicle of Higher Education may prove useful for preparing for a conversation with your funding agency.