I was formerly ret, and have since changed to Holy, but even if you want to continue down the ret path, loot the holy paladin gear from Kara and shore em up. Because I didn't and after I made the Holy switch (which you might have to do from time to time depending on what your guild needs), I didn't have enough good healing abilities. I now have to rerun Kara and other instances a few more times to get up to snuff.
In short, Kara has awesome pally healing gear and sucky ret gear. PvP your ret set and Kara your Holy set as back-up.