Probably the most important thing to have is business and management experience, not necessarily in aviation. Start small,keep the overheads down, do as much as you can yourself, and don't take on any big financial committments until you have been operating for at least a year and have seen the trends. And treat your staff right! They are the ones who will make and break you.
When I got my AOC five years ago I was lucky, the CASA guy assigned to me was helpfulness itself, I applied for the AOC at our local office and it was all done in a matter of a couple of weeks and a couple of hundred bucks (wrote the ops manual myself, it was a pretty straightforward application).
Now the local office is gone, I have had someone else assigned to me, and the "Service centre" (what a joke) require about three months to reissue the AOC when it runs out, and they nearly didn't renew it because I didn't have what they considered to be the necessary qualifications, ie time in commercial ops other than instructing, to be the CFI. Never mind a clean bill of health in safety, and ten years as an instructor....
It finally came through 24 hours before the old one expired.
So no, don't expect them to be helpful.