Before volunteering, I suggest sitting down and getting an understanding of what the job expectations are, limitations, with or without police powers of arrest, armed or not, etc.
Different towns treat the subject differently.
Per MGL (which PDs rarely follow), Aux. PD is supposed to fall under the Civil Defense agency in town and answer directly to them, no police powers and no weapons.
Many/most PDs have the Aux. POs reporting to the FT PD, directing traffic at churches, "volunteering" (mandatory) at all the road races, various town events, unpaid, no weapons and no arrest powers. Check to see if they outfit you or if you have to pay for your own uniform and gear (I did and the shirts/pants cost $40-80 each, so it gets expensive to be a volunteer).
Some may require that you be on the Civil Service roster and use you to screen for permanent PO candidates.
In every case you are cannon fodder, no coverage if injured/killed on duty, etc.
I was a Reserve PO, with full police powers, armed, trained, etc. But for 17 yrs I was REQUIRED to give up my July 4th holiday (used to be 3 days of "volunteer" work in town, ~16 hrs on duty) every year. I had to get "special permission" to skip one year as it was my MIL's 65th Birthday so I could be with my Family. This was in addition to many Saturdays and Sundays as well as evenings, Halloween and other events/holidays each year.