The western jetty is lightly guarded, with only two guard at a good distance from the actual dock. The multiple pathways into the center of the island allow you to move around in cover and get off headshot on the enemies with a Spec-Ops weapon.
Although the southern jetty is not great for an aggressive approach, the buildings provide enough cover for you to follow the shore east and then use the camera to hack the data from the guard. You can then hack the cameras until you find the guard in the northeast on a small sandy path. In order to get the guard to head up toward the ctOS center you will need to hack the junction box to create an explosion for him to investigate.