firs to break last to make is ABSOLUTELY BACKWARD when working with your car battery.
Think of it this way, if you connect the pos after the neg, and your wrench touches a grounded metal part, you will get more than a little spark. If you really ground out, you can discharge the entire contents of your battery. That's a lot of juice. Your wrench may become very hot, may even weld to the body. You can end up with burns, the battery can explode under just the right/wrong conditions.
Conversely, if you connect the positive first, then the neg terminal, you can touch whatever you want as many times as you want, since there is not a complete circuit, the worst that can happen is that you will s****e your knuckles.