What are the Buddhist teachings on how best to live a married life?

A few other selections from the Pāḷi texts, since they seem to be what people respond to (I'm not bothering to offer my own translations this evening, these are by Thanissaro and can be taken with a pinch of salt). From the Rhinoceros Horn Sutta:

For a sociable person
there are allurements;
on the heels of allurement, this pain.
Seeing allurement's drawback,
wander alone
like a rhinoceros.

One whose mind
is enmeshed in sympathy
for friends & companions,
neglects the true goal.
Seeing this danger in intimacy,
wander alone
like a rhinoceros.

From the Piyajātika Sutta:

"That's the way it is, householder. That's the way it is — for sorrow, lamentation, pain, distress, & despair are born from one who is dear, come springing from one who is dear."

From the Ariyapariyesana Sutta:

"And what may be said to be subject to aging... illness... death... sorrow... defilement? Spouses & children... men & women slaves... goats & sheep... fowl & pigs... elephants, cattle, horses, & mares... gold & silver are subject to aging... illness... death... sorrow... defilement. Subject to aging... illness... death... sorrow... defilement are these acquisitions, and one who is tied to them, infatuated with them, who has totally fallen for them, being subject to birth, seeks what is likewise subject to aging... illness... death... sorrow... defilement. This is ignoble search.

And I could go on and on, citing dozens of texts which emphasise that, although there are some concessions to lay people in some places, they are not really taken seriously as Buddhist practitioners, nor expected to make much progress in the spiritual life. Certainly they are not expected to be liberated - the conditions are simply not in place for lay people. The best they can hope for, according to this point of view, is to generate enough merit to obtain a better rebirth.

Mahāyāna sects were more accommodating of lay people, but the extent of this is often over-stated. For example the idea that Mahāyāna was primarily a lay movement is now thoroughly discredited. It was essentially an offshoot of mainstream monastic Buddhism. For an overview of recent research on Mahāyāna history see: David Drewes, Early Indian Mahayana Buddhism I: Recent scholarship.

Of course one is free to pursue what the Buddha calls the "ignoble search" (i.e. marriage, relationships, socialising, career, and all that lay oriented stuff). But it is ignoble and it does not lead to liberation. Of course because supporting monks is the principle source of merit for laypeople, the monks have made a few concessions over the years to keep the lay people onside. But the basic message of Buddhism has not changed in many centuries, "Seeing this danger in intimacy, wander alone like a rhinoceros."

The exception is the kalyāṇa mitta one who is able to guide and support one in the spiritual life. But it's pretty clear who this might be - the Buddha is the template, so it really refers to arahants and other members of the ariyasaṅgha.

The phenomenon of modern lay people redefining the Buddha's message to fit the preconceptions of a modern world, with undigested lumps of popular psychology, so that more or less any lifestyle is seen as conducive to religious practice, is at best unfortunate. It is a serious misrepresentation of the Buddha's message as far as it is represented in the Pāḷi texts. In Buddhism one cannot have one's cake and eat it.

In DN 31 the Buddha saw a young householder "with palms together held up in reverence, [...] paying respect towards the six directions: that is east, south, west, north, lower and upper."

The Buddha, after asking what he was doing, said:

"But, young man, that is not how the six directions should be worshipped according to the discipline of the noble ones."

...and then, proceeded to explain it. At some point, he said:

"And how, young man, does the noble disciple protect the six directions? These six directions should be known: mother and father as the east, teachers as the south, spouse and family as the west, friends and colleagues as the north, workers and servants as the lower direction, and ascetics and Brahmans as the upper direction.
[...]

"In five ways should a wife as the western direction be respected by a husband: by honoring, not disrespecting, being faithful, sharing authority, and by giving gifts.

"And, the wife so respected reciprocates with compassion in five ways: by being well-organized, being kindly disposed to the in-laws and household workers, being faithful, looking after the household goods, and being skillful and diligent in all duties.

In this way, the western direction is protected and made peaceful and secure.

Here is a quote from the Anguttara Nikaya where the Buddha explains how to live together in a marriage.

53 (3) Living Together (1)

On one occasion the Blessed One was traveling along the high- way between Madhurā and Verañjā. A number of male and female householders were also traveling along the same high- way. Then the Blessed One left the highway and sat down at the foot of a tree. The male and female householders saw the Blessed One sitting there and approached him, paid homage to him, and sat down to one side. The Blessed One then said to them:

“Householders, there are these four ways of living together. What four? A wretch lives together with a wretch;739 a wretch lives together with a female deva; a deva lives together with a wretch; a deva lives together with a female deva.

(1) “And how, householders, does a wretch live together with a wretch? [58] Here, the husband is one who destroys life, takes what is not given, engages in sexual misconduct, speaks falsely, and indulges in liquor, wine, and intoxicants, the basis for heedlessness; he is immoral, of bad character; he dwells at home with a heart obsessed by the stain of miserli- ness; he insults and reviles ascetics and brahmins. And his wife is also one who destroys life . . . she insults and reviles ascetics and brahmins. It is in such a way that a wretch lives together with a wretch.

(2) “And how does a wretch live together with a female deva? Here, the husband is one who destroys life . . . he insults and reviles ascetics and brahmins. But his wife is one who abstains from the destruction of life, from taking what is not given, from sexual misconduct, from false speech, and from liquor, wine, and intoxicants, the basis for heedlessness; she is virtuous, of good character; she dwells at home with a heart free from the stain of miserliness; she does not insult or revile ascetics and brahmins. It is in such a way that a wretch lives together with a female deva.

(3) “And how does a deva live together with a wretch? Here, the husband is one who abstains from the destruction of life . . . he does not insult or revile ascetics and brahmins. But his wife is one who destroys life . . . she insults and reviles ascetics and brahmins. It is in such a way that a deva lives together with a wretch.

(4) “And how does a deva live together with a female deva? Here, the husband is one who abstains from the destruction of life . . . he does not insult or revile ascetics and brahmins. And his wife is also one who abstains from the destruction of life . . . she does not insult or revile ascetics and brahmins. It is in such a way that a deva lives together with a female deva. [59] “These are the four ways of living together.”

When both are immoral, miserly and abusive, husband and wife live together as wretches.

The husband is immoral, miserly and abusive, but his wife is virtuous, charitable, generous. She is a female deva living with a wretched husband.

The husband is virtuous, charitable, generous, but his wife is immoral, miserly and abusive. She is a wretch living with a deva husband.

Both husband and wife are endowed with faith, charitable and self-controlled, living their lives righteously, addressing each other with pleasant words.

Then many benefits accrue to them and they dwell at ease. Their enemies are saddened when both are the same in virtue.

Having practiced the Dhamma here, the same in virtuous behavior and observances, delighting [after death] in a deva world, they rejoice, enjoying sensual pleasures.

-- AN: 53, p. 443-445, Bodhi translation

The Access to Insight website has a number of related translations and essays;

Suttas

• How to ensure that you'll be with your spouse in future lives: AN 4.55
• Spouses' duties to each other: DN 31

Essays

• "A Single Mind" (Fuang)
• A Happy Married Life: A Buddhist Perspective (Dhammananda)
• Nothing Higher to Live For (Nyanasobhano)
• Buddhism and Sex (Walshe)

It all seems to boil down to "be ethical". Although on the other hand ideally one would not get married, but would take up celibacy and reject family life. For example in the Cūḷahatthipadopama Sutta the Buddha says:

so tena saddhāpaṭilābhena samannāgato iti paṭisañcikkhati — ‘sambādho gharāvāso rajopatho, abbhokāso pabbajjā. nayidaṃ sukaraṃ agāraṃ ajjhāvasatā ekantaparipuṇṇaṃ ekantaparisuddhaṃ saṅkhalikhitaṃ brahmacariyaṃ carituṃ. [MN 27; i.179

And having become possessed of faith [from hearing the dhamma] he thinks: household life is crowed and dirty; having gone forth one is wide open. It is not easy to live the religious life, so perfect and pure like a polished shell, while living in a home.

In short the best way to do marriage, is not to do it all, but to dedicate yourself to practising the Dharma.

This question is similar to a previous one:

What does a traditional Buddhist wedding look like?