[patrickt]

Really, your toughest decision is whether you want the volt meter switched or not (meaning, do you want the gauge displaying the volt level with the key off). You generally have it switched in most cars, but I've seen a couple of Cobras that have it wired hot all the time, but have a battery disconnect (which most of us have anyway). There are handy advantages to having it hot all the time but you just disconnect the battery when you're not driving the car. It's up to you.