Things divers need to consider in prevention of diving accidents:
1. Careful selection and predive physical examination of the divers.
2. Careful selection of the appropriate equipment and gas mixtures for the dive.
3. Careful predive planning to identify potential problems and formulate contingency plans.

Predive planning includes:
—Proper scheduling to avoid fatigue, to remain within O2 limits, and to avoid excessive decompression obligations.
—Consider water temperature, current, workload and visibility.
—Maximize efficiency and safety by careful division of each diver bottom time packet.
—Thorough knowledge of all equipment to be used by the divers and support personnel.
—A thorough knowledge of the decompression schedules must be obtained by all concerned.
—Preparation to diagnose and treat all diving accidents as they arise.
—Proper diagnostic and therapeutic equipment must be on the scene and operable.
—Have proper communications setup with backup medical and recompression facilities.
—Have a transport plan available.
—Have a source of 100% oxygen available during transport.

Physical standards of divers can be found on this web site in many places. Generally, the requirement is for a vigorous, emotionally mature individual free of any systemic disease or conditions that are well-controlled. Dives should not be undertaken with temporary acute illnesses, such as ENT
infections, hangovers, substance abuse, bronchitis or ‘pneumonia’, seasickness or excessive fatigue.

Careful evaluation and control of the type of Underwater Breathing Apparatus to be used on the dive.
References here include:
US Navy Diving Manual – Various Volumes.
Bevan, J. Commercial Diving Equipment and Procedures in Bennett and Elliott, “The Physiology and Medicine of Diving”, 1993