Use a berserk dart on a brute and you'll find the brute taking down a few enemies before he's finally brought down himself, or simply passes out following the duration of the darts effectiveness. Using a berserk dart on a normal enemy will get them killed by a nearby guard with relative ease. These are the larger guards who wield and axe and throw bombs at Edward. The most effective use of berserk darts is against brute enemies. Berserk darts make an enemy go crazy for a short time, attacking anyone nearby, then eventually passing out. If there are a group of enemies, it's generally better to use berserk darts instead of sleep darts. A sleeping dart will put him out of commission long enough to move out of his line of sight, or climb the watch tower and knock him out. The guard is too high to reach immediately, and you probably don't want to alert the other enemies by shooting the guard. Sleep darts are best used when spotted by a guard in a watch tower. Usually it's long enough to get to the enemy and knock them out (or simply escape to a safe distance), but there is a limited time before they wake up if you can't get over to them for the knock out. An enemy will also only be sleeping for a moderately short period of time. Sleeping darts put an enemy to sleep, but alert any other enemies who happen to see the sleeping body. There are two types of darts available to Edward: sleeping and berserk. If there's anything blocking your view, it can be difficult to see another enemy attacking Edward, which makes it far more difficult to execute a successful counter before their attack. It's highly recommended to move the camera to a position in which you can clearly see all around Edward when he's surrounded by enemies. Against armed guards, disarming them is also beneficial if you need a gun or want to avoid taking fire while you're attacking other enemies. This is especially useful if you need to kill a specific person, and get interrupted by another enemy in the process. If you're surrounded by a large number of opponents, it may be easier to simply stun the opponent, then get back to the target you were focused on. Just make sure you highlight the next enemy and attack him or her immediately following a kill. Not only does this eliminate one of your attackers, it also allows Edward to transition into what is fondly referred to as "kill mode" in which he can kill nearby enemies with a single attack. In most cases, you want to simply kill the enemy after a successful counter. Immediately following a successful counter, you have a variety of options including: kill the enemy (Square or X), use a tool on the enemy (Triangle or Y), disarm and stun the enemy (X or A), or throw the enemy (Circle or B). If you press Circle (PlayStation) or B (Xbox), Edward performs a counter. If you see a red mark above an enemy's head, it means that he or she is about to attack Edward. When you're in the midst of combat with Edward's swords, in most cases you'll be fighting more than one opponent. This makes swordplay a very good option for combating enemies at close range. It takes Edward quite some time to reload after expending his initial ammo stock. This isn't Call of Duty where you can reload in a virtual instant.
You can use guns to take down your enemies, but they alert any other enemies in the general vicinity, and you have to worry about ammo restrictions and reloading. There are many instances in which you must engage in combat as Edward, whether you're boarding a ship, or on land fighting off guards or natives.
Once you've played a bit of AC4: Black Flag, you may want to delve a little deeper with these advanced tips!