My advice is keep an eye out for everything. Under good conditions the CT raids are easy and fun to heal, but if you get a group that doesn't dodge or screws up mechanics you may have to get ready to spam heals and raises.

Another thing is make sure to double check your stance, diurnal is usually our default as AST since regens are great. If your co-healer is a SCH, make sure to be diurnal sect, as our noct shields overwrite their galvanize and vice versa. Be the opposite of the other AST, since same stance asts will overwrite each others aspects. And if a WHM co healer, do it based on gear or personal preference. I like shielding if the other heals is a WHM, but our aspect regens stack on WHM regens.