We work with a Rescue group for Basset Hounds.
If you are trying to raise money for a charity - make sure that this is clearly posted in your event advertisements, and banners / signs at the event site.
Some ideas:
-50/50 Raffle - get some paired-up ticket rolls, have one or two drawings per day. Winner gets 50% of the take from ticket sales.
(We've even had some winners "donate-back" all or most of their winnings.)
-Prize Raffle - See if any local shops/vendors are willing to donate stuff that you can use as prizes / raffle-off. Then sell tickets at a reasonable price, but enough that your charity actually makes some money.
(NOTE: With any charity raffle - be sure to comply with any state / local policies. In Wisconsin, we have to obtain a "Raffle License" from the state.)
-Decorate some "danation jars" and place them prominently at places where people will sit while they eat / listen to the band. (we use lids with a slot, and silicone the lids on)
We DO charge a reasonable entry fee - this helps to cover the cost of tent rental etc.
Make sure you have a place set-up that is secure, where you periodically bring the cash boxes / change jars, etc.
Be sure to keep Separate Cash Boxes for each event / raffle, etc. and record your results before making any deposit etc.. This way, if this will be an annual event, you can see how well each event / raffle went, and can make intelligent decisions for the next year.
(With a charity - it looks bad to be handling the money out in the open, plus you do not want to be a target for would-be thugs and opportunists.)