Pain/bruise/swelling. Bones have most of their living structure on the outside surface, like bark on a tree. Bone bruises can produce significant pain, but breaks will add some blood pooling (bruising) & swelling to the mix. The more dramatic the fracture the more likely a visable deformity & rarely bone parts will stick out thru the skin.
Pain. Unless you have some congenital disorder that doesn't allow you to feel pain then pain would be the most common symptom of a fracture.