pinning help?

wow, okay, i totally might sound like an idiot here, so sorry about that. but im not sure where to look for this sort of thing.

basically, whenever i pin my fur and sew it, the seam is always off a little on the other side because of how i pinned it. i have no clue how the logic behind pinning works and how to compensate for what im pinning or something, but im about to do my bodysuit and i really dont want anything to look crooked :<

can anyone help me out?