This leads me to my second point...
Lesson #2: Secure loose cables or they WILL get caught!!!
These are, of course, rather "common sense" things to say/do but when you're in-the-moment and just itching to jump into the water/sea you may forget to do this (as I did).
So take a moment, get your dive buddy to check your gear. Besides obviously checking each other's BC, regulators and other dive equipment, take a few moments to make sure you secure (tuck-away/tie-together/tape along side) any camera cables, mono-pods, cases etc. floating behind you.
It wont take long, and believe me it'll save you more time in the long run, not to mention it'll save your shot/clip.
The video below shows me getting snagged onto coral just as I am doing a follow shot into a world war two Japanese wreck.
This is what happens WHEN YOU DO NOT SECURE YOUR GEAR.....
As side note, wreck diving is fun but can also be dangerous if you don't know what you're doing. Being underwater and in a confined space can cause inexperienced divers to get disorientated and panic. If you're new at diving, please don't go into a wreck alone, and definitely do NOT be filming or trying to fumble around with cameras or settings or cables. The last thing you want is to get tangled up with cable/coral, in zero visibility (because you have panicked and kicked up all the dust and silt around you), and be in an enclosed area/wreck where no one can see or help you. Always be safe.