Slowly, I am not being a smarty. I found if you put a opener under the lip of the lid and turn sideways (kinda clockwise), not like you would if you were opening a bottle, go slowly, as soon as you hear a hiss, stop for a few seconds, then finish taking the lid off. Also, put a towel over the lid will help with spills.
Why not use a jar opener - it's the other side of a "church key". That's what they are made for.Leave the jar sitting on the counter. Take the end of a spoon, or a butter knife or something, and use it to pry between the top thread of the jar and the metal lid... Keep a hand on the lid so it doesn't go flying..