^ has the right of it with PI, when I get a proc I'll either pop it between my next casts or pocket it if a tank hit is coming up. It's useful but too erratic to really build a game plan around it, just try to keep using it and you'll be doing fine.

Outside of that, the best tip I can offer is to try and maximise the usage and value of your cooldowns. Try to avoid pocketing them for too long. WHM is an absolute beast in dungeons now, with decent cooldown usage I'm holding 3k+ dps on trash pulls without any large pulls.