Most common mistake is synchronizing too often. In most cases what you want to do is sync infrequently -- 1-2 times per second. Rest of the time use interpolation.
I did that in the MPGSK (Multi-Purpose Game Starter Kit) available on the Asset Store. It's a physics-driven game kit where I sync pos/rot/velocity only when somethinig happens (like explosion), or infrequently (4 times per second there, but even that is too much). The renderer is using a spring lerp to move after the rigidbody, so it's always ever-so-slightly behind, but any irregularities in movement get smoothed automatically.