Another good tip if you are new, is to use power strips and extension cords, and be far away from the circuit the first time you power it up if you are at all suspicious of it.
Also, if you can, work in pairs. That way someone can always unplug it if it gets bad.
which reminds me, if someone else is getting shocked and can't let go (god forbid, my wishes for everyones safety)
DONT grab them or the thing that is shocking them and get shocked too. PULL THE PLUG or HIT THE SWITCH ASAP.
If you cant, pull them by the DRY clothing or shove them with a DRY chair or someting.
And if you are getting shocked and can't let go, Smashing the offending item sometimes helps. Anything to reduce or cut off the power.
And wearing goggles is a really good idea. I wear goggles anytime i solder, use a power tool of any sort, go anywhere near the mains, or work on anything DC that could have high power.
DON'T let anyone tell you you don't need a particular safety item or procedure. If YOU think you need goggles, insulated tools, an insulated mat to stand on, somebody watching so you don't screw up, a CATIII rated meter, You probably do.
do not ever let anyone reduce your personal standard of safety for any reason, Even if seems "cool" or "tough" to do it the dangerous way. use whatever you need to be safe
If you are careful, nothing bad will happen. for further info, ask someone who knows what they are doing and see:
http://sound.westhost.com/articles/electrocution.htmEDIT:Got rid of trailing . making url not work. Sorry guys!