American Alliance of Museums
The Alliance offers several resources for building advocacy skills, learning about Congress, making your case and getting involved in museum advocacy. Resources include sample case statements, tips to meeting and communicating with elected officials and online learning on a number of advocacy issues.
Nonprofit Vote provides a lot of useful information nonprofits can use to help determine how they can engage with candidates and their elected officials.
Texas Commission on the Arts
The Texas Commission on the Arts shares an advocacy toolkit that may be useful to small museums. It shares information on case statement, guidelines for writing and visiting decision makers, lobbying and the law for nonprofits, and samples to help communicate with decision makers.