I've volunteered at a few things. Sorting through clothes at a charity shop, volunteering at a kitchen, and with Meals on Wheels. Every time, I was, at first, given nothing to do. So I would start doing what looked like needed to be done, or just doing what everyone else was doing. And I would get told off for doing something, or doing it wrong ... and then shown how it should be done ... until someone else told me off because I wasn't doing it the way THEY thought it should be done. So I would then be back to having nothing to do. Would never get thanked for volunteering, or even offering to volunteer. And the last straw was, at one large, internationally known charity group, being told that they didn't want "my type" hanging around. I didn't even care to find out what they assumed the type of person they thought I was, because by then I was done with volunteering.
Granted, these have only been my experiences, and many other people would have had positive experiences in volunteering. So I would say try it, if you want to. But don't let them walk all over you or take you for granted.