Make sure you wear gloves and eye protection, remove all jewelry, and work in a cold environment - mercury evaporates (slowly) at room temperatures and above, so I would work in a ventilated space. Also, look out for any particles floating on it, especially red-colored bits, as that can be explosive. Keep any vials out of direct sunlight, which is what forms those explosive bits. Mercury was the reason hatters went mad, BTW, so handle with care. If you do spill any, have some copper or brass wool handy to mop up those tiny balls of it that scatter everywhere.