With an abundance of caution, I always use a safety chain connecting the bow eye and the trailer, in addition to the winch strap/cable.
If the trailer is long enough, I prefer a set of stern tie-downs connecting the stern of the boat with the trailer, rather that a ratcheting strap.
They are at least as secure and not prone to vibrating in the wind flow. On my current rig, I am using gunnel tie-downs since the boat extends well beyond the trailer frame, even though the bunks extend past the transom. Finally, I always secure the motor in some fashion; either a transom saver or bungeed to the trailer frame.