One really effective way to get the community involved with the effort is to have a library fundraiser event. So many people aren't even aware of the libraries in their community, and don't take the time to visit as often as they should. Hosting an event can not only draw attention to the library, but can get people actually inside the building, where they can see all the fantastic things that are offered, as well as the things that need improvement, the things that library fundraising would benefit.
Advertising is an important part of fundraising, as it's important to get the message out so that people attend your event. It's important to make the event sound enticing - mentioning any food, drinks, or entertainment is a sure-fire way to get people to take notice of what you're doing. If you can get some volunteers to help with all aspects of the event, like offering to prepare the food, bring the drinks, and help distribute the advertising leaflets, you can keep costs down and make even more profit for the library. The more you can get volunteers to assist you and donate their time and effort, the more your library fundraising event will be a success.