Ive done volunteering in India and Kenya and didnt know anyone out there before i went...met friends for life in both countries! The idea of going out there completely on your own is what makes it so exciting, not knowing who you will meet etc and seeing new faces. I found people who have taken their friend/s with them on volunteering as tend to be a disadvantage at times as they already have that click and tend to try less with the rest of the new volunteers which can be off putting for others. What ever you feel comfortable with tho