I don't deal with risky chemicals but do deal with electrical stuff from time to time.
Other than the usual, my at-most important safety procedure is to NEVER WORK ALONE. I must have someone present in the house where a yell or scream can summon unaffected person(s). Depending on what I am doing, I occasionally have someone visually observing me while I work. In such cases, the person is explained of what to do in case something happens - each and every time.