Well, just looking at your Lodestone profile and *assuming* that's the gear you're wearing, it's totally wrong. I don't know if you have any of the Hoplite main set pieces yet, but if you don't you should at the very least be wearing your AF armor. (go do you job quests!) That stuff you have on as of the last time the Lodestone updated has garbage for defense, so healers are going to have to spam heal you to keep you up because your defense stat is so low.

Once you're properly geared then it may be worth going over certain mechanics. But basically you'll want to use Flash liberally and spread your enmity combo attacks around on your non-primary targets to keep them stuck on you, the latter bit assuming sleep isn't being employed.