It is virtually impossible to anticipate all of the hazards involved with automotive maintenance and service but care and common sense will prevent most accidents.
See Figures 1, 2, 3 and 4
Fig. Fig. 1: Screwdrivers should be kept in good condition to prevent injury that could result if the blade slips from the screw.
Fig. Fig. 2: Power tools should be properly grounded
Fig. Fig. 3: Using the correct size wrench will help prevent the possibility of rounding off a nut