Where should I start for flatbed? Company or O/O?

You really should work for a flatbed company before jumping in with both feet. I respect how you feel and your interest, but unfortunately there are too many drivers out here flat bedding who have no idea what they are doing. Sure they know how to drive a truck or back into a parking spot(some obviously don't). A driver running a flatbed, step or any of the sorts who lacks experience is the most dangerous. They expose themselves everywhere. Under-secure loads and the cost can be fatal. Get experience, haul as much freight as you can, learn the laws and the way of the flatbed land.