Here is a galvanized commercial grade chain link fence with barbed wire. Barbed wire is generally installed with three strands and on a forty-five degree angle. Here, the barbed wire is angled outward. The general rule being; face out to keep out, face in to keep in.
The terminal posts, on this installation, were capped with a malleable corner arm. It is more common to extend the terminal post upward and attach the barbed wire to brace bands. Here however, due to the small size of this enclosure, a continuous look to the barbed wire was more appropriate.