As DAO combat is quite MMO-like, something from the MMO school of fighting applies here as well.
Lesson 1: Pulling. Never just charge into a group of enemies. Stay out of the enemies aggro range (their spotting range) and try to pull one or two of them at a time. This can be achieved with ranged weapons and spells. Target the one enemy that's furthest from the group. If possible, maneuver into a position, where you're on the opposite side of the main group when compared to your "straggler" (i.e. the less bunched-up enemy) or at least in "that sector". This is important, because this way your target can charge you without going closer to his buddies (and possibly pulling them too). More often than not, only the one you targetted and perhaps few of his closest buddies attack you. Now you can dispatch them and possibly even recover your Health and Stamina/Mana back to full, before tackling the rest and/or pulling the next couple of enemies. If the enemy is an archer, usually only he (and perhaps someone right next to him) attacks you with arrows, while his buddies just stand around clueless. Note: Do NOT target the boss of the group (yellow when others are white, etc.). He'll usually pull the whole group with him, making this tactic useless.
As you may have noticed, I used the word "usually" quite often. That's because, these don't work 100% of the time. They sometimes do, sometimes don't. But when they do, they make larger fights/groups of enemies much easier to manage (and win).
Lesson 1: Pulling. Never just charge into a group of enemies. Stay out of the enemies aggro range (their spotting range) and try to pull one or two of them at a time. This can be achieved with ranged weapons and spells. Target the one enemy that's furthest from the group. If possible, maneuver into a position, where you're on the opposite side of the main group when compared to your "straggler" (i.e. the less bunched-up enemy) or at least in "that sector". This is important, because this way your target can charge you without going closer to his buddies (and possibly pulling them too). More often than not, only the one you targetted and perhaps few of his closest buddies attack you. Now you can dispatch them and possibly even recover your Health and Stamina/Mana back to full, before tackling the rest and/or pulling the next couple of enemies. If the enemy is an archer, usually only he (and perhaps someone right next to him) attacks you with arrows, while his buddies just stand around clueless. Note: Do NOT target the boss of the group (yellow when others are white, etc.). He'll usually pull the whole group with him, making this tactic useless.
As you may have noticed, I used the word "usually" quite often. That's because, these don't work 100% of the time. They sometimes do, sometimes don't. But when they do, they make larger fights/groups of enemies much easier to manage (and win).