First off, don't approach the car wearing enough jewelry to rival Mr. T!
That said, I'm not the foremost authority, but I remove the negative (ground) lead first.
I figure logically, if I'm using a long wrench or ratchet, I don't want to remove the positive (+) lead first anyway, because the opposite end may contact some metal portion of the engine compartment, and with the negative lead still connected, my tool completes the circuit (ZZZZAP...if you can get a mental picture of this).
In the future, I think the safest way to do this is to get one of those battery disconnect gizmos that attaches directly to your battery terminal. It has a big knob that you loosen, which disconnects the battery. I've seen it in many catalogs, including www.griots.com.
Enjoy your trip!