1. map out your cooldowns for raids. Encounters will go through the same sequence of mechanics and raid busters every time, on the dime. So you should plan when you'll be using rampart, sentinel, hallowed ground, and so on. You can go the extra mile and map out cooldowns for your co-tank, so then you can plan ahead and see when is the best time to switch for getting the most out of cooldowns for everyone.

2. str VI materia on accessories, and direct hit for your left-side equipment.

3. If you're OTing, you should be in sword oath the entire time unless adds are involved. When LEARNING encounters, it's acceptable to be in shield oath for extended durations, but once you have an encountered learned, you shouldn't be using shield oath for much, except maybe momentarily to grab adds and use a single RoH combo.