PLD first strike. Am I Pld'ing wrong?

[JonBigwood]

Hi, I wouldn't use Stoneskin routinely in the middle of the fight. It's most effective when you are at top health, and least effective if you are in low HP, and it takes time to cast, so in trash mobs you won't need it if you are at top health, you may need to move or do other things, and the healer can heal you if necessary. If you are in low HP probably it's best to cast Convalescence, Rampart, Sentinel, Hallowed Ground etc. (whichever available or adequate) and wait for the healer to cure you while you maybe avoid AOE, stun the attacker or something. On the other hand, it's the best "healing" spell you have, so it's the best thing to use it if the circumstances are right.
At the start of the fight, if there is a WHM, his Stoneskin is stronger so better have him cast it instead of doing it yourself if he is willing (hopefully he will be.)