Don't run an engine in a garage or anywhere else without proper ventilation - EVER! Carbon monoxide is poisonous; it takes a long time to leave the human body and you can build up a deadly supply of it in your system by simply breathing in a little every day. You may not realize you are slowly poisoning yourself. Always use power vents, windows, fans or open the garage doors.Don't work around moving parts while wearing a necktie or other loose clothing. Short sleeves are much safer than long, loose sleeves; hard-toed shoes with neoprene soles protect your toes and give a better grip on slippery surfaces. Jewelry such as watches, fancy belt buckles, beads or body adornment of any kind is not safe working around a car. Long hair should be hidden under a hat or cap.Don't use pockets for toolboxes. A fall or bump can drive a screwdriver deep into your body. Even a wiping cloth hanging from the back pocket can wrap around a spinning shaft or fan.Don't smoke when working around gasoline, cleaning solvent or other flammable material.Don't smoke when working around the battery. When the battery is being charged, it gives off explosive hydrogen gas.Don't use gasoline to wash your hands; there are excellent soaps available. Gasoline may contain additives which may enter the body through a cut. Gasoline also removes all the natural oils from the skin so that bone dry hands will suck up oil and grease.Don't service the air conditioning system unless you are equipped with the necessary tools and training. The refrigerant, R-12, is extremely cold when compressed, and will instantly freeze any surface it contacts, including your eyes. Although the refrigerant is normally non-toxic; R-12 becomes a deadly poisonous gas in the presence of an open flame. One good whiff of the vapors from burning refrigerant can be fatal.Don't use screwdrivers for anything other than turning screws! A screwdriver used as a prying tool or chisel can snap when least expected, causing bodily harm. Besides, you may ruin a good tool when it is used for purposes other than those intended.Don't use a bumper jack, scissors or pantograph jack that comes with the car for anything other than changing a flat tire! If you are serious about repairing and maintaining your own car, then one of the best investments you can make is in a hydraulic floor jack of at least 1 1 / 2 ton capacity.