There are basic, common-sense things related to safety that are de facto rules when working on machinery: Wear safety glasses or face shields when grinding or cutting metal. Wear ear protection around noisy equipment or grinders. Wear gloves while cutting or welding. Common sense stuff that at minimum reduces discomfort and at maximum prevents injuries.
Over the years I've learned there are many ways to get injured or scare yourself in a shop that go beyond the normal, basic safety considerations. In no particular order, and without admitting guilt, here are some situations I've "been around" that gave me pause and reason to re-think how I do things:
-When wearing a hooded sweatshirt with a drawstring, don't use a bench-mounted grinding wheel/buffing wheel. If you lean forward, one of the drawstrings can get caught in the spinning wheel, which immediately reels your face toward the whirling wheel much faster than you can reach the "off" switch.
-Don't use a welder while wearing athletic shoes. Sparks will land in the cloth segments of the shoe and not only burn through, but in some cases set the cloth on fire. The flame is colorful, but it's disconcerting to look down and see flames on top of your foot.
-Don't use a grinder when doing a quick repair job in your garage or shop at home if you're wearing rubber flip-flops. Metal filings that fall into the flip-flop will embed themselves in the rubber and then transfer to the tender flesh of your foot as you walk back to the house. Trust me, your wife will not be sympathetic, and may actually laugh at your discomfort.
-Never assume you can locate and unroll a garden hose faster than a trash fire can develop under a combine or hay baler on which you're welding or torching.
-When welding in a sitting, crouched or kneeling position, always look in advance for folds or creases in the fabric of your pants that might catch and hold globs of molten metal against treasured body parts. Because they will.
The list of odd ways to cause yourself pain or injury while working on machinery is nearly endless. The secret is to use all available safety strategies, anticipate "surprises," and...if you survive...learn from your mistakes. The first time is an accident, the second time is just plain stupid.