I would advise new users to not even enable "manual" in their flight control selection. Leave it at GPS/Atti/Atti.
And, IOC is a great tool-but learn its limitations. For example, the aircraft needs to be 10 meters away from you, to use Home Lock...but, for course lock, it doesn't. Also, the manual says the aircraft needs to be running for 30 seconds before you can enable Course Lock. I've not tested that.
Home Lock is great for the first time fliers. You will lose orientation, and sometimes it happens very quickly. The second you realize you don't know what direction the aircraft is pointed-switch into GPS(if you were in Atti mode), and Home Lock, add power to climb, and pull back on the stick. Once your Phantom has come back into a position that you can figure out it's orientation, then you can go back to normal flying.
This one feature has saved me countless times. Remember; Altitude is your friend, and the ground is your enemy. So, keep some distance from your enemy.
It's good to always have an "emergency drill"..or an immediate series of steps you always take, in the event you pull/push on a stick, and the Phantom doesn't go the direction you thought it would(might be pointed towards you).
In that situtaion-immediately switch to GPS mode, center the right stick, and add power to climb, while switching to Home Lock.....pull back on the right stick, and wait for your Phantom to recover/return. when the right stick is centered in GPS-even if your Phantom was flying forward quickly, it will come to a fairly quick stop, and just hold position.