Volunteering at Halloween
If you are thinking of volunteering your time and energy in any capacity this Halloween, the first thing you need to consider is whom you are going to benefit. The second thing to consider is whose permission you will need, for Halloween is largely a children's holiday (regardless of its origins) and you need parental or other authorized permission to interact with children who don't already know you.
There are, of course, ways to benefit adults on Halloween. Hospitals, hospices and residences for the elderly may all be good places where people are unable to entertain themselves in an appropriately spooky fashion. Reading, telling or enacting ghost stories for these folks may bring them some joy. You will need to find out who needs what, get those pesky permissions from the administration of the establishment in question, and refrain from giving anyone more horror than their health - mental or physical - can handle. You can ask schools (well in advance, if possible) whether a Halloween performance would be something to which they'd be open. If a school's drama department is overworked, volunteering to make costumes, props or non-intrusive suggestions might be appreciated.
If you have a local organization you would like to support - anything from Boy or Girl Scouts to the Elks to the Rotary Club to the B'nai B'rith to your local religious, political or social entity - you may suggest to the proper administrators that you would be happy to decorate, cater, sell tickets to or even organize a Halloween event for that entity. (Your town's Chamber of Commerce may be able to point you in the right direction if you can't choose.) The possibilities are endless. How about a bake sale in which all the goodies are orange and black, or a costume dance, a storytelling slam, an apple-bobbing contest or a costume-sewing bee?
However, if you work well with children, enjoy their company and respect boundaries, you may wish to volunteer to go trick-or-treating with kids whose parents have no time or inclination, or who have no parents, or who for other reasons will not get to go out unless some responsible adult volunteers to take them. Knocking on doors to see who needs your services is probably a bad idea. Joining an unaccompanied band of trick-or-treaters on the street is probably an even worse tactic.
One thing you might do - again, as far in advance as possible - would be to contact the Chamber of Commerce, city hall and/or school administrators and ask them to publicize your availability for such a happy task. You will want to have an information sheet prepared, with your contact information, any background you have working with children, relevant volunteer experience, references if possible and the details of what you are offering and when. Don't be surprised or dismayed if a background check is called for; minors are a protected species, as well they should be.Once you've chosen how you wish to volunteer, and made arrangements to do so, then it is up to you to come through as promised (none of that "well, I'm not charging for this so it's okay if I'm an hour late" or "it's not a real job so I can change my mind at the last minute" stuff!) and have fun.