What should I disconnect before resetting service light

[rainmaker23]

OK... I'm a beginner... what should I disconnect before resetting the service light on my 95 Volvo 850? I don't want to get shocked.

ALSO, and probably more dangerous: I have a loose ignition switch. That is, I ahve to jiggle it a bit after starting to make the ABS light go out and to get it out of Park.

I suspect that I might need to replace the switch (or just clean it, if that would help), but the same question applies: What do I need to disconnect before I shock myself into next week?

Thanks!