This is the basic guide, comprised of “Do” and “Do not” in a group melee combat.*
*Any suggestions to improve it are more than welcome.
Introduction.
-There is only one tactical principle which is not subject to change. It is to use the means at hand to inflict the maximum amount of wound, death, and destruction on the enemy in the minimum amount of time.George S. Patton
Group combat isn’t a chivalrous duel and the goal is to kill as many of your opponents as possible using every advantage at your disposal.
Situational awareness is probably the most important aspect - do not fixate on one opponent; instead try to gain an advantage in several directions, however short-lived it can be.
The second is to be proactive and not reactive - the enemy should adapt to your decisions and maneuvers and not the other way around.
2 vs 2 Combat-Each man must not think only of himself, but also of his buddy fighting beside him.George S. Patton
“Do” try to create a mismatch as early as possible by flanking one of them

“Do not” face the enemy in one line.

Still, if it does happen, try to advance on one flank (preferably left, esp. if the second opponent has a shield) and create a cushion between you and your opponent, then turn and help your teammate.
3 vs 3 Combat-Some goddamn fool once said that flanks have got to be secure. Since then sonofabitches all over the globe have been guarding their flanks. I don't agree with that. My flanks are something for the enemy to worry about, not me. Before he finds out where my flanks are, I'll be cutting the bastard's throat.George S. Patton
A bit more complicated than 2 vs 2 but the idea is the same – gaining an advantage.
Being exposed to the attacks from two directions is preferable to being exposed to the attacks from three directions.
“Do” extend flanks in a reverse Wedge formation to create a mismatch in the enemy center.

“Do not” let the enemy to perform this maneuver.

We’re addressing the basic stuff here but more advanced tactics do advocate using the Wedge formation to, let’s say, separate one opponent from the rest.
Having Numerical Advantage.-No bastard ever won a war by dying for his country. He won it by making the other poor dumb bastard die for his country.George S. Patton
Golden rule – never make a mistake of facing your teammate when attacking an outnumbered enemy. Meaning that the angle between you and your teammates should be anything but 180 degrees. This will prevent the unnecessary team hitting.
“Do”


"Do not"
Fighting Against Multiple Opponents.When outnumbered, you can choose two ways to handle the situation: to defend or to use a more aggressive approach.
Defense
-Fixed fortifications are monuments to man's stupidity.George S. Patton
The key here is to prevent simultaneous attacks. Strafe left and right in order to face one opponent at the time.
“Do”

“Do not”

When cornered, dash between the opponents to force them to face each other. This will result, more often than not, in enemy team hits.

The exception would be if you have a shield and your teammate is coming to the rescue from behind their lines. Here, your goal is to fixate them on you thus exposing their rear to the ally.

Aggressive stance-In case of doubt, attack.George S. Patton
In case that you chose to attack instead of defending, surprise them by attacking an unsuspecting enemy. Usually he’s the one trying to outflank you while you’re pretending to charge his teammate.
“Do”

“Do not”
Last but not least*
*If your name is Skinnyjean, feel free to skip this part. The rest shall proceed as if nothing happened.
Spoiler
-It is a popular idea that a man is a hero just because he was killed in action. Rather, I think, a man is frequently a fool when he gets killed.George S. Patton
This is the best tactics when heavily outnumbered
