Any volunteer experience is a plus! But try to volunteer at a Clinical or Retail pharmacy setting where you can actually get hands on experience. I have been working at an outpatient pharmacy for about 1 and a half year now. It is really nice to see what pharmacist do and in this way you can learn a lot from them. I hope that helps!
I volunteered at the inpatient pharmacy of the local hospital in my town. Since I was not an actual technician there, there wasn't a whole lot of real work i could actually do (like the kind of work that a real technician/pharmacist would do). So I basically shadowed the techs and pharmacists. Other times, I would put drugs away or file patients' records too. It was a good experience that helped me to see what kind of work I'd be getting into as a pharmacist or tech. I voluteered there for about five months, then got a job at a retail pharmacy.