Never used aix but general raid practice...
Understand the documentation. Preferably use a separate channel for each drive in the array set, would recommend a "hotspare", which can be place on any of the channels ( which would mean one of the channels have two drives).
Do not consider placing a tape drive on any channel of an array adapter. Document all settings during your array configuration.
Mark your drives and cables. Provide, and maintain, as much cooling as possible for your array; beside the age of your drives, heat is the next threat to array longevity. I have about 20 arrays, my servers ( Supermicro) maintain the drives a few degrees about room temperature; due to this, some luck ,and Seagate I have not replaced a drive in over a year