Here are a few tricks my friend taught me, makes a big difference between 1700 and 1900+
First off is the interrupt macro
1.Download Nature's Enemy Cast Bars
Natur EnemyCastBar | World of Warcraft Addons | World of Warcraft @ Curse.com
2. Hit "esc" in game and go to keybindings. Find Focus Target and set it to z
3. Make a macro saying this:
#showtooltip Earth Shock(Rank 1)
/cast [target=focus,nodead,harm] Earth Shock(Rank 1); Earth Shock(Rank 1)
Now what this will do is when you are in arena (This actually works better as elem) you can dps the focus target that your team calls out, but at the beginning target a healer and hit z so he is focused for your macro. You can dps down the target your team calls out and your enemy cast bars will tell you when the healer is healing and all you have to do is press the macro and it will target him and cast rank 1 earth shock and interrupt him.
SECOND MACRO WOOOO
This one is common sense. Its basically a purge macro so you don't have to do any extra work targetting things and only have to worry about hitting a few buttons.
Go the macro page and type this:
/target TEAMMATESNAME
/assist
/cast Purge
Just spam that at the beginning of the fight, or when you are fighting a priest (they will throw up sheild and are a pain in the ass for your partners to dps through) and have fun :]