Don't believe or expect that marriage is a 50:50 division of labor or responsibility. It's a give-and-take proposition that does not need a balance sheet. (It does tend to balance over time.)
Laugh a lot: With each other, at each other, at yourselves.
Sometimes, being right may not be the thing to insist on.
Remember, that once a hurtful word is spoken, it can never be taken back.
Evaluate your values BEFORE you get married to make sure that you are compatible. Many couples do not discuss their dreams and expectations.
Realize that the love changes over time. But love is love - go with it and have fun.