Don't forget to look at how well your two families, especially the better halves, get along. A business is a family affair and any tension can lead to big argument and problems down the road. If they are not involved in the decisions, both of you may regret it in the future. Finally, get a business lawyer involved, as they will be able to point out things that neither of you have thought about. It may cost money up front, but will save you both in the future.