I bought a

SKYREAT Copper Parabolic Antenna Range Booster for DJI Phantom 3 Standard / SE Controller Transmitter Signal Extend  it is a #1 best seller on Amazon & it works only on a P3
My question is what is the best way to point the antenna Up or down ?

Typically you would have it up but a few on here point theirs down to clear other mounts/mods. As long as it's pointed perpendicular to the AC your good to go. Remember though that the Skyreat will only help with AC control and won't do anything for video feed.