[Fin Mike]

As I'm reading some of these stories on this board and I must say that most of this stuff is completely avoidable with a little common sense. I am a spearfisherman. Spearfishing is extremely dangerous and highly problematic. Take the blood in the water and the shark aspect out of it, and you still have a recipe for disaster. As I first started to dive, I would ask my (much more experienced) buddy about some of the pitfalls of diving and how I could avoid them. His response was "where do I start". That was a good answer, because only experience can teach someone properly how to deal with life and death situations.
First, 99% of all accidents can be avoided by using common sense and knowing and feeling comfortable with your equipment. I can't be more clear than that. It will save your life. Second, wear a redundant breathing system such as a pony bottle, not spare air. Spare air will not save your life if you are 125' down. A 30 cu ft pony will. Enjoy yourself (that's what it's all about) but be prepared for the worst. I almost always get vertigo upon ascent, but I've learned to deal with it. A newbee that got vertigo at 100' would FREEK OUT. It is very concerning for the inexperienced, let alone getting your reg knocked out of your mouth by a speared 60 lbs cobia at 115'. The last thing I would like to say is DO NOT PANIC. Panic will kill you. Confidence not only in yourself, but also in your equipment goes a long way. Don't be stupid, be safe.
Don't go into decompression (deco). Always continue breathing, and do not ascend more than one foot per second and you will be OK. If your new, stay above 50 ft, and get comfortable with your equipment. I can't state this enough. Never blow anything up at depth that you want to hold on to. This could surely bend you.