When you have a couple with different last names, how do you alphabetize? Should you list the woman first the alphabetize by the last name of the husband?

I assume you're talking about hyphenated names. This is always confusing to me too.

With the same last name you can say: Thomas and Louise Black, but if Louise's name is Louise Red-Black, how do you do it?

I could be wrong, but I would alphabetize it as Thomas and Louise Black ignoring the hyphenated name unless I was going to address something to Louise only.