Newbie wants to be a better tank

[MahoSenshi]

1. Don't be a gladiator - do your job quest and unlock paladin. Bare classes are useless beyond 30.
2. Use Shield Oath, it helps with defences and aggro generation.
3. Watch aggro meters (under the job icon in the party list) and do your aggro combo (Fast-Savage-Rage) on the right targets.

Problem solved.