I kinda agree with Hurri: if you are doing something you don't really appreciate but only in the hope of getting hotties, it probably won't work.
Your behavior will betray your real intention on the long run, and the HBs will stay away from you like the plague.
I was once "sitting" in a French press class at my current American university. French being one of my two mother tongues, it was a little difficult for me to justify my presence in the class when I talk with all the cute girls. I was sincerely interested in "seeing how French is taught in American universities" although the huge concentration of really cute HBs made me decide to spend sometime there.
For diverse reasons, I didn't get any girl from the class. For example, the cutie who I focused on the whole time turned out to like tall (I'm 5'9
) and beefy (I'm like 140 lbs
) guys and I figured it out only at the last minute. And many girls from the class were just going to France for exchange programs while I basically stayed here in the US as an exchange student...
Anyway even now I don't consider that I wasted my time since I was sincerely interested in the class. So I would say that whatever volunteer work/charity you are looking for, you NEED TO LIKE WHAT YOU DO!