Beached
Head to the beach and profile the three targets first. The area has one camera in the middle and cameras carried by guards. After profiling the targets, it will be better to take out the guards and approach your targets silently. Spec Ops weapons are the best here. Just use Focus and headshots to eliminate armored targets.
Out of the Woodwork
Head to the wood mill and use the cameras in the area to find the target. Work your way around the guards or take them out silently until you get near the target and knock him down. The area has a lot of hiding places and the guards are placed far between each other so it shouldn't be that hard to take them out one by one. Shortly after, a second target will arrive. Make sure to tag him before moving in to eliminate him.
You can get around the first target by using the nearby lift to get to the upper ledge and jumping off behind the cover where he's leaning to get his attention. You can safely knock him down from there. Finally, eliminate all remaining non-targets to complete the mission.
Burning Bridges
There are three targets and a lot of enemies. Switch views from various cameras so you can tag and profile the targets. You can find the first target near the entrance. Kill the nearest enemy and take out the sniper on the crane. You can knock out the first target afterward.
The second target is located at the base of the bridge construction site. Just get in range to a camera and switch views until you spot him. You can take out the immediate guards then jump to the water to get near the second target. Go upstairs and find a crane with a barrier. Hide there and activate it to reach the other side of the bridge. Keep in cover and hack the cameras until you profile the last target.
Decapitated
Go uphill overlooking the graveyard and take out the sniper. From there, you can hack a camera so you can profile your target. After finding him, you can kill all guards and leave him last. He will attempt to escape. Chase after him and take him down.