Just my two cents but it'll help to track boss hp as percent. Pretty much every fight in the game follows patterns and phases. Seeing exact percent will help you out.

For example, if you know your dragoon tends to get hit by a certain attack and you know its coming, you could withhold your ogcd in case they need it. If a boss shifts to a raid wide aoe at some% hp then you could pop regen or shields in preparation so that you're not panicking when the attack begins.