Eve isk: Fighting on the day the Avatar is weak against does well to enhance your chances
FFXI Bard Abilities: Job abilities mean special strengths which are unlocked after the required number of levels are completed. These can be reused Eve isk after a specific amount of real-life time has passed (re-use time for each ability is different).
The homework you do before going into the fight is absolutely pivotal. Don't think of the Avatars as pushovers, you would need to have some helpful rings and food, anything that boosts your stats in the fight. Fighting on the day the Avatar is weak against does well to enhance your chances.
Where to find the FFXI Titan: To find Titan in FFXI, go to the NPC named Farrol, near the drawbridge in Port Bastok. He should be standing with a Taru, so you are not likely to have any problems spotting him.
The NPC will give you a tuning fork. Trading it with him will teleport you to the Cloister for the fight, and the rest will be history!
However, when you are looking to fight to acquire other FFXI Avatars at level 20 fights, the Carbuncle can be your best friend. It will do the tanking for you and die many a times during the process.