A Hybrid Priest takes both from the Blood tree and the Holy tree. Depending on how supportive or PVP inclined you want to be, your build may differ. 

Builds (By NeonRedFish)

There are 2 builds, Holy Priest Blood Support and Blood Priest Holy Support. 

First, the Blood Priest Holy Support. This one is my favourite because it gives me the ability to buff, and the stengh for PvP. You use the the left and right branches on the Blood tree, and the right branch and Awakening skills of the Holy tree. 

The Holy Priest Blood Support is a supportive build, meaning you can buff, but will not have the ability to heal. The left and right branches of the Holy tree and the right branch of the Blood tree.