Sex sex and more sex. The more frequent and creative, the better.
Open communication and trust is the best way I know.
Kill the spouse, it's not divorce, just "separation".
Hard work by both people which is the hard part usually someone is lazy
Be willing to do whatever it takes to work things out.
I've come to believe it is impossible, which is why after the one I'm in at the moment, I'm done with marriage.
Be completely subservient
where there is an issue talk about it.. don't wait for things to get better or change
Without communication you have nothing
Religious dogma keeps some married couples together. Nothing like fear of going to Hell to make a person do something.
find someone who is honest, trustworthy, faithful, kind, generous, will to grow and stay together forever.. and be those same attributes yourself.
Katharine Hepburn said
"If you want to give up the admiration of many men, and replace it with the criticism of one, then by all means, get married...."
If you never get married, you can never get divorced...it's the only surefire guarantee.
Take your marriage vows seriously