I'm curious because a few people in the past have mentioned not knowing exactly where to measure, and the differences can be quite big...34" hips vs. 36" hips.

I measure my bust right under the armpits. For my waist, it's a bit harder since it's not that defined, so for clarification I bend to the side and place the measuring tape where my torso bends. I measure my hips where my bum sticks out the most.