I'm not an expert at all, but I have been able to take care of my family on a 'ministry-salary'. So here's the answer I gave him. I did these things when my wife and I first got married, and I continue to do them six years later (and counting).
- Get the book: The Complete Financial Guide for Young Couples. Read it and dialogue about it with your spouse (or fiance). It is one of the best and most used books my wife and I received in pre-marital counseling.
- Don't spend money you don't have. This means avoiding purchasing on credit like its the plague.
- Budget like a maniac. When you don't have to consistently ask "Which budget category should I put this in?" you're close to having enough budget categories.
- Talk about every purchase with your wife. You have to be on the same page.
- Go grocery shopping every two weeks. When switched to this from shopping every week we saved SO much money, even though we didn't change what we bought. (There's probably another lesson here, something like: "Put yourself in front of consumable items as little as possible.")
- A second book I would recommend is First Comes Love, Then Comes Money. It is all about financial communication (which in marriage can be more important than the finances themselves.)