Here's a hint: It's the quality, not the quantity of endorsers that can make the difference. Yes, your friends and neighbors are important. It's good to show that people you know, ordinary voters, like you. But that long list of names most people never heard of is only impressive to the few who know them well and respect their opinions. And those few may never see that their neighbor Joe Schmo supports you, if Joe's name is just one in a sea of names occupying valuable real estate on the back of your mailer.
So what endorsements count? There are roughly three categories: Organizations, elected officials and opinion leaders.
Certain organizational endorsements are heavily sought by candidates depending on what issues are important to the electorate. The Sierra Club is key if you want to clue in environmentalists and nature lovers that you are the one who will stand up to conserve wetlands, open space or urban parks.
Nurses imply integrity and compassion. Teachers show that you care about the next generation and the quality of their education, even if education isn't a top priority in your race.
Business and development organizations say you may be open to new growth and growing the economy.
Firefighters and police show you are trusted to keep your community safe.
Think about what each organization wants in a candidate and make sure you meet those criteria when seeking the endorsement. Then use the logo of the organization (or newspaper - these also can be important in local as well as larger elections - but caveat - make sure it's ok with the organization to use their logo on your materials. The Sierra Club for instance has a specific logo just for their endorsed candidates to use. Newspapers generally don't let their trademarked materials be used) proudly on your material. If you can get a quote from a leader of the group stating that you are the one who will carry their priorities forward, that's a big plus.
See if your Congressmember, State Senator or local city council person will endorse you. People who are held in high regard because of their positions will count the most. Those who hold similar positions to the one you are running for are also key. Do the members of the school board you are running for support you? Get a quote from the President of the board on why you would make a good member. Use their photo alongside their testimonial. This will stand out to the voter a lot more than just listing them in a long queue.
These are people whose opinions matter. They may be heads of community organization, homeowners associations, or environmental or civic groups. Attractive pictures of these people, alongside a quote about your superior ability to hold the position you seek will be seen, read and remembered by the voters.