Don't tighten drill chucks by hand....
Always secure material to drill press via vice, clamp, bolts whatver before drilling... yes, that was me.
Do not open multiple drawers on a tool chest at the same time... Also me.
um... If using an impact w/ a wobble do not run the nut or bolt all the way off, stop before and remove completely by hand, things do go flying.
When lowering car lifts make sure that lift has completely disengaged safety latch on both sides before lowering (I did catch it in time...)
One at the expense of my old coworkers at a marine. When summerizing a boat do not leave unattended at idle, bilge pumps = slower than thru hull fittings.