I wouldn't PvP right now in Rets current state. You'd be feeding wins for opposing teams. But if you insist to try, here's some addons I recommend.
Clcret - If you aren't comfortable with your rotation yet.
Weakauras - to track Inquisition and what not.
BattlegroundTargets - for Battlegrounds and RBGs. Good luck getting into a RBG.
Bindpad - for keybinds and macros
GladiusEx - For Arena
KAHolyPower - Cause the default Holy Power bar is stupid.
OmniCC - To see numbers for ability cool downs.
Quartz - For a better cast bar.
As for macros, use as much mouse over macros as possible. It helps to maintain maximum dps while providing utility. For example.
Just change Flash of Light to whatever ability you want to use. Things like Hand of Freedom or Word of Glory. The more of these you have the better. But I will repeat, Ret PvP is a free kill to anyone you go up against. Our healing and damage is nowhere near where it should be in PvP.
/cast [@mouseover,help,nodead][@player] Flash of Light