I always unplug the PSU from the wall and never use any anti-static mat, wrist band, whatnot. Just be sure to disperse any static electricity you may have built up before you start working. I usually just touch metal items before starting work, like the computer case, a metal door knob, something like that. I also do all my work on the dinner table, after I clean it off of course. Generally don't have carpet in that room so it's hard to build up static electricity while working on the PC.