1. Tanking - Always Use Tiger Mode:
Your main focuses are to Stay Alive, Constantly Build Up Chi, and Keep the Mobs Aggro'd.
SPAM Flesh Ream to make the mobs attack you and not your fragile party members. Flesh Ream does stack bleeding damage, which is what helps maintain aggro over time. Try adding a couple attacks/skills that don't consume Chi in between Flesh Reams to prevent your Chi bar from being empty.
You could use Roar if there are multiple monsters you have to tank. However, it sets the aggro to a set level, usually much lower than if you were spamming Flesh Ream. Plus, Roar has a long cooldown time (60 seconds), so use it only when you get mobbed.
Use Devour only when you have aggro’d the mob previously (Devour only creates greater hate if you are the one it is attacking). It's also great for reducing the enemy's physical defense, but use it sparingly because it costs quite a bit of Chi, which can run out quickly when used in combination with Flesh Ream.
Use Sunder to recover lost HP.
Use Surf Impact once in awhile to reduce the mobs’ speed, in case they choose to run away from you and attack your party members. That way, you’ll have more time to lure the mobs back to you.
Also use Frighten if the mobs are tough/dealing a lot of damage to your party. It's a great way to gain Chi as well.
Whenever an enemy is casting a skill (especially magic), quickly use Alacrity of the Beast to cancel them.
Constantly have Beastial Rage activated to build up Chi for skills.
Invoke the Spirit, which reduces damage by 90%, helps a lot when tanking tough bosses.
2. Training:
a. Soloing
If you’re poor, use Tiger Mode.
1st use Alacrity of the Beast to cancel monster skills, then use normal attacks.
Cast Sunder whenever you’re running out of HP.
If you’re rich with lots of potions/charms and decent gears, use Humanoid Mode to kill mobs faster.
Here's a nice combo for melee mobs:
1st use Mighty Swing to stun, then Slam to knockback
Next, use Beastial Onslaught to reduce evasion while the mob is coming back to you, then Penetrate Armor to reduce defense
And finally, 3 normal attacks
Repeat
b. AoE partying (lv 60+)
A "zhen" party or a "perfect" AoE party consists of 3-6 squad members using continuous damage and healing arrays, and 2-3 "lurers" who pull high lv mobs into the array at an extremely high rate. This results in a high exp/sp gain at the cost of the players' HP/MP charms.
The Barbarian's role is to be the lurer and also to give the HP buff (Beast King's Inspiration) to the party whenever it runs out.
Luring for AoE squads as a barbarian does take a bit of practice. Your job is to round up many mobs just by running near them, using attack skills occasionally to keep the mobs following you, while leading them back to where the wizards/archers/clerics have their AoE set up. This can be done in humanoid or tiger mode. Humanoid is easier because you'll have more AoE skills to use, but tiger mode is faster due to higher movement speed.
As you know, the mobs will usually follow you when you get close to them. However, the mobs will stop following you after they travel a certain distance. What you gotta find out is how much distance the mobs travel before they stop following you (usually 5-8 seconds of running). Once you find that out, all you have to do is use an attack AoE (Roar, Sunder, Surf Impact, Slam, Swell, or Firestorm) on them before that time, while luring them to the Damage Dealers.
You can also lure using a land mount as long as the mobs keep following you. Just note that if you travel too far without using skills on the mobs, they will stop following you.
Try to lure in a circle if possible, or lure from the farthest point inward.
3. PVPing
Humanoid Mode
Use Blood Bath and Beastial Onslaught when dealing with high evasion players.
Use Mighty Swing as much as possible to stun; Penetrate Armor to reduce their physical defense
Use Armageddon wisely. Treat it more like a final attack rather than a starting one. You'll either be half-dead or have hiero cooldown after using it..
----Beastial Onslaught and Slam can be chained with Armageddon when dealing with multiple enemies.
----Beware when fighting those with the Venomancer's buff, Bramble Guard, which reflects 60%+ of your damage and can easily kill you before you know what hit you.
Tiger Mode
Best used when chasing people because True Form adds movement speed.
You can cast Surf Impact, catch up to them, then return to humanoid mode to attack.
Alacrity of the Beast is highly useful to cancel their skills.
Using Sunder to recover your HP while fighting is also very handy.
If you're able to use MP pots/charms, then switching back to humanoid mode after using Invoke the Spirit or Sunder can turn the match completely to your favor.
~And the rest will come with in-game experience