A snippet from the Churches for Middle East Peace Website's page on Advocacy Tools:

"When asked, most Congressional staff say that constituent visits to the Washington office (97%) and to the district or state offices (94%) have “some” or “a lot” of influence on an undecided member of Congress, more than any other influence group or strategy. ("Communicating with Congress: Perceptions of Citizen Advocacy on Capitol Hill" from the Congressional Management Foundation)

In-person meetings with your members of Congress and their staff are the single most influential form of grassroots advocacy, especially if it is part of a long-term effort to cultivate a relationship with your elected officials. The great news is that you don’t have to travel to Washington to meet with your member face-to-face. Members of Congress spend several weeks a year in their home districts to be accessible to their constituents. Don’t pass up the next opportunity to meet with your representative and senators to advocate for peace!"

Also see the CMEP's "What You Can Do" flier.

Also see Maryknoll's flier

Also see the comprehensive "Communicating with Congress: Recommendations for Improving the Democratic Dialog" report
 by the Congressional Management Foundation and "Communicating with Congress: How the Internet has Changed Citizen Engagement" report.