I found these ten golden pieces of advise on how to maintain a happy marriage life from part of a fatwa on askimam.org

Ibn Abbas (Radhiyallahu Anhu) narrates that Rasulullah (Sallalahu Alaihi Wasallam) has said, “We have not seen anything that creates love between two individuals such as nikah.” (Ibn Majah)

There are many ways of increasing love between the couple. Consider the following ten points to maintain a happy marriage and control the instinct of dispute.

1. Fear Allah: It was the noble practice of Nabi (Sallalahu Alaihi Wasallam) to make the spouses aware of the fear of Allah before performing a nikah by reciting the verses (Al-Nisa 14, Al-Ahzab 69, Aali-Imraan 101) from the Qur’an. All the verses are common in the message of taqwa (fear of Allah). The spouses will be first committed to Allah before being committed to their partner. There can be no doubt in the success of a marriage governed by the fear of Allah.

2. Never be angry at the same time: Anger is the root cause for all marital disputes. One Sahaabi came to Rasulullah (Sallalahu Alaihi Wasallam) and sought some advice. Rasulullah (Sallalahu Alaihi Wasallam) replied, “Control your anger.” The same advice was rendered three times.
(Mishkat Pg. 433; H.M. Saeed)

3. If one has to win an argument, let it be the other: Nabi (Sallalahu Alaihi Wasallam) said, “Whoever discards an argument despite being correct shall earn a palace in the center of Jannah.
(Mishkat Pg. 412)

4. Never shout at each other unless the house is on fire: Luqman (AS) while offering advice to his son said, “And lower your voice for verily the most disliked voice is that of a donkey.” (Surah Luqman 19)

5. If you have to criticize, do it lovingly: Rasulullah (Sallalahu Alaihi Wasallam) said, “A Mu’min is a mirror for a Mu’min.”
(Abu Dawood Vol 2, Pg 325 Imdadiya)
Advice with dignity and silently.

6. Never bring up mistakes of the past: Nabi (Sallalahu Alaihi Wasallam) said, “Whoever conceals the faults of others, Allah shall conceal his faults on the day of Qiyamah.”
(Mishkat Pg. 429)

7. Neglect the whole world rather than your marriage partner: Nabi (Sallalahu Alaihi Wasallam) confirmed the advice of Salman (Radhiyallahu Anhu) to Abu Darda (Radhiyallahu Anhu) for neglecting his wife. “Verily there is a right of your wife over you.”
(Nasai 2391)

8. Never sleep with an argument unsettled: Hadhrat Abu Bakr (Radhiyallahu Anhu) resolved his dispute with his wife over feeding the guest before going to bed.
(Bukhari 602)

9. At least, once every day, express your gratitude to your partner: Nabi (Sallalahu Alaihi Wasallam) said, “Whoever does not show gratitude to the people has not shown gratitude to Allah.”
(Abu Dawud, Pg 662; Karachi)

10. When you have done something wrong, be ready to admit it and ask for forgiveness: Nabi (Sallalahu Alaihi Wasallam) said, “All the sons of Adam commit error, and the best of those who err are those who seek forgiveness.” (Tirmidhi 2499)

(Taken from Al-Mahmood)