This tactic requires some fine skills, high agility equips, and most importantly, a good knowledge of the map. It requires the player to have either a Blunderbuss or a Double Barrel Shotgun for the best effect, but Revolvers work just as well.
This tactic is basically summed up by its name: Death from above.
To execute this maneuver, you must jump/fall from a high point above a player, landing on them while firing. Make sure to aim your weapon down and fire the entire time, not letting up till a few moments after you hit the ground. You can do this from any high point where players can be standing directly underneath you. Make sure to move as soon as you land, and always be prepared for the tactic to fail - that way, if it does do so, you won't be a sitting duck for weapon fire.
For Sandtown, the easiest place to do this is in one of two spots - either from the ledge that is directly below the crashed plane, or by jumping off of the wooden plank that connects the two buildings up to the ammo supply crates on the opposite sides of the map. As players don't tend to stand still for very long, make sure you time your jump correctly for a clean headshot.
You can do this tactic from the center support where you can jump off of the steel walkway onto players below.
This map is Death from Above paradise. Any of the elevated walkways are perfect for this tactic, where you can just jump down from above and kill the player with a clean headshot. The ramps also provide elevation, though it is suggested you are more careful while trying to pull off this maneuver on them - if you miss, you are a sitting duck for approaching players.
Here, All the upper levels are places for you to execute the tactic. However, like at Royal Garden, the chances of scenario 3 happening is large. However, due to the fact that the upper walkways are generally covered, so you better hope that your opponent can't react fast enough, unless you will probably die.
This place, like Sandtown, is very big, making it hard to excecute this tactic. Camping beforehand will help alot.