positioning hair pieces in blender

Hey guys, I've tried to make some hair edits before with buns and pigtails and such but I can never get them in the right positions. I try using location of x y of the other pieces but they still don't look symmetrical and it's really frustrating me. I've tried watching a few tutorials but it won't work with what i'm doing.. 

EDIT:

ah I think i kinda figured it out. i'm not sure why it didn't work the other times, but now it does :D