Sometimes, all you need to incentivise people is to create a little competition. Selling calendars, pens, school supplies etc. are an age-old fundraising trick, but adding a little competition to them is a great way to ramp up efforts, and create a better outcome.
Regardless of what your fundraising activity is, creating a contest based around this activity will inspire more people to become involved, and will ultimately cause more people to participate. For example, assume that your fundraising effort is selling candy bars. You can create a contest based on who sells various amounts of this candy bar. A person that sells the minimum of say ten candy bars receives a particular prize, a person that sells twenty gets another award, and this continues for various prizes and various amounts of candy sold.
Adding a contest to a fundraising effort creates a new more fun element to it, and pushes members within your local chapter to get more involved within it. With a small investment in prizes, you can exponentially increase the outcome of your fundraiser.