Dr. Gottman's 7 Principles of Successful Relationships. Here are some other tips: Always make each other and your relationship a priority because you are the foundation upon which you will build and grow your family. You need to be solid; Always speak positively about each other when out with others or when each other isn't present. This all boils down to respect for one another and the relationship.
I have lots of friends in unhappy marriages for the sake of "keeping their family together" You can be married a long time but an unhappy marriage is not a successful marriage. It just confuses your children about what they should expect out of their own relationships someday. What is worse than your unhappy marriage? Watching your child suffer through what they were taught by watching you.
Relationships (of any kind - friends, family, lovers) that are based on anything less than honesty are nothing more than superficial exchanges. Things that have been shackled, and denied the light that truth brings, will never grow or expand. As difficult as it might be to accept, someone who lies to you does not respect you. Someone who does not respect you can't really be your friend. As disappointed as you may feel, there is immense value in accepting this.