Sell Something. It is so obvious.
Candy bars, wrapping paper, cookies - even "pre cookies" what others call cookie dough. Spend time reseraching these programs and make sure to read the section on Selecting a Fundraiser.
I sold M & M's and LOTS of them - I think it was over 13 cases for our dance studio - yep, I was top seller. I even did this fundraiser when it was against the rules at our middle school. Total covert candy selling operation, I had a very large purse. Now, while publically I cannot endorse breaking rules - I did, and I became top seller.
The advantage to an organized fundraiser is being able to chat with your representative - they may have ideas for success. Just remember they're probably working on commission. Ask for the phone number of another group they have worked with and call them - ask the group leader how successful the fundraiser was and would they do it again. Then ask the most important question - What would you do different?
Disadvantage to this type of fundraiser: you have to pre-order the candy and that means you have to sell it! You don't make any money until you hit your break even point, so make sure to see if the company has a buy back policy.
Another alternative: Avoid the middle man - does anyone in your group have access to a discount warehouse or wholesaler? Buy direct from somewhere like a Sam's club and save on delivery - you also can start small and go back for more candy - it's a good way to have control over how your sales are going.