1. Learn not to fear birth.
Sometimes Dads get a bad rap for being insensitive or detached during labor and birth. I think it's just fear of the unknown and not knowing what to expect. Men like to see themselves as competent and fearless, so not knowing what's coming usually throws them for a loop and they need to escape. If he hears in class that women use moaning and rhythmic movement to work through the contractions, and then he sees it happen in a birth video, he won't be scared when it happens to his wife.
2. Find ways to support mom.
I don't like the idea of Dad as a labor coach. Especially if this is his first baby, he won't instinctively know how to help her. If he's unprepared his well-intentioned idea to "rescue" her might be to encourage pain-relieving drugs, which are neither necessary or safe in many situations. I've found that when Dad knows ways to help, like rubbing shoulders, a cold washcloth, or loving words, he can truly be a support instead of a sabotager.
3. Understand labor language. A hallmark of late labor is that a woman becomes much less communicative. This is not only normal, but necessary for a safer birth. The woman needs to shift her brain over to the more instinctual part of it when she gives birth naturally, and this primal brain doesn't speak well. You, as her next of kin, need to listen to what her caregivers are saying and be able to respond as she would. When you hear, "break her water" you will understand what that means and if it's a procedure your wife would agree to and be willing to accept the consequences.
4. Show her you care. Nothing is more sexy than a man who takes care of his family. I know you'd rather be watching football than sitting in a class discussing breastfeeding and postpartum bleeding, but it really means a lot to your wife that you are making the effort. A couple who has spent time focusing on their child together will feel more connected when it comes time for the birth.