Welcome aboard! Learning is key as well as practice.
There has been a tremendous amount of experience, lessons, ideas and thoughts previously shared on this board. I would highly recommend (assuming you have the time) reading through the previous threads and posts. In particular, Gary has on several occaisions captured the essence of what we do in some pretty powerful descriptions of previous dives. It is not fun, but as a firefighter, the experience and training we receive on the fire side, does help in performing PSD.
Good luck and stay safe!
Dan