I should note that I had to tweak Mercurio's 2 step macros a bit to work better for my stats.
I would suggest using a raid dummy with a single toon, make sure "#showtooltip" is at the top of your macro, then watch closely as you DPS, to see if the macro is getting hung anywhere on a cooldown and watch your lightning shield charges to see when Earth Shield is going off.
Also make sure Flame Shock is recasting before it drops, but not overlapping TOO much. Ideally, I think you want it to recast when there's 1-2sec left on it.
With a macro, it's nearly impossible to get Earth Shield to always cast at the ideal (7-8 charges) time, but you can still get pretty good DPS if you keep an eye on those things I mentioned.