I would say as one who's quite keen on DIY certain electronics that I used at home and the ones used by close relatives, I've got a lot to say about safety measures.
There are certain things that I do before I even begin to work.
Firstly, I ensure that I do all work in a ventilated environment because of issues with fumes. I also don't miss out on wearing safety glasses that help to protect my eyes. I would always recommend having the first extinguisher around just for safety.
During working time, I don't plug anything into the electricity when I am working and if I need to disassemble any parts, disconnecting the batteries /caps and discharging them is a must.
Doing some of these little things is mainly for safety reasons while I am working or before I even resume working.