The prior article in this cluster, Can you make up your own prayer?, answered the threshold question. The answer was yes. This article is about how to do it well.
What follows is not rules. It is a synthesis of what Christians have actually done with prayer for two thousand years, distilled from the practice of the desert fathers, the medieval Latin collect tradition, the Reformation prayer books, the Methodist and Puritan extempore traditions, and the modern liturgists who have continued to write prayers for new situations. The Christian tradition has been remarkably consistent about what makes a prayer hold up.
There are seven things it has settled on.
1. Address God, don't perform
The single biggest mistake in modern devotional writing is confusing prayer with motivational speech. A prayer is spoken to God. It is not a teaching tool aimed at the reader who happens to be praying along, and it is not a thinly-disguised meditation. It is direct address.
If your prayer ever turns into an instruction to yourself or to the room ("Lord, help us remember that we should be kind to others"), it has stopped being prayer and started being a homily. The fix is simple: speak to God, not at the listener. The Lord's Prayer does this perfectly. Every sentence is addressed to the Father. None of it is aimed sideways at the disciples standing next to Jesus.
2. Ask, don't demand
The grammatical mood of Christian prayer is the petitionary subjunctive. Words like may, grant, help us to. Not the imperative make this happen. Not the assertive we know you will.
This is more than a style preference. It is a theological commitment. Christian prayer asks God to act. It does not instruct God on what to do, and it does not claim outcomes on God's behalf. The 16th-century collects of Thomas Cranmer in the Book of Common Prayer are masterclasses in this register. They ask, and they leave the answer to God.
Compare "give us peace in our hearts" (asking) with "give us a successful presentation" (asking for a specific worldly outcome). The first is a prayer. The second is a wish. The tradition has been wary of the second for a long reason: it makes prayer transactional, and a transactional prayer is one that can be refuted by a bad day at the office.
3. Stay theologically clean
A good prayer stays inside what mainstream Christian theology has actually said. It does not promise on God's behalf, does not invent doctrines, does not substitute therapeutic language for theological language.
If a prayer reads as a positive affirmation with "Lord" added at the start, it is not really a prayer. "Help me to be my best self today, Lord" is therapy. "Grant me grace today to do the work you have given me, and the patience to do it well" is prayer. The difference is that the second one knows whom it is addressing and what it is asking for in Christian terms.
The seventeenth-century Anglican divine Lancelot Andrewes, in his Private Devotions (Preces Privatae), built each personal prayer around scriptural language and traditional theological categories. He did not invent. He composed within what the tradition already had. The result is some of the finest English-language prayer ever written.
4. Concrete, not abstract
The Lord's Prayer says "give us this day our daily bread," not "provide for our needs." It says "forgive us our trespasses," not "please address the issue of human shortcomings." It says "deliver us from evil," not "may we be protected."
Specific is better than general. A prayer that names the actual thing being asked for, the actual fear, the actual hope, is a stronger prayer than one that gestures at the situation in the abstract.
The desert fathers in 4th-century Egypt taught their disciples that vague prayer was the easiest kind of prayer to do badly. The mind wanders because it has nothing concrete to hold. Specificity is a discipline.
5. Short
Most of the great prayers in Christian history are under fifty words. The Lord's Prayer is fifty-seven words in its standard English form. The Jesus Prayer is eleven. Cranmer's Collect for Purity is fifty-three. The Collect for Peace from Morning Prayer is sixty-eight.
A prayer that runs to a paragraph has usually gone wrong. Either it is performing rather than addressing, or it is asking for too many things at once, or it has stopped being a prayer and become an essay with vocative interjections.
If your prayer runs long, cut it. Repeat the cutting. The version that survives will almost always be stronger.
6. Plain, dignified language
Not contemporary slang. Not King James pastiche. Not the therapeutic register of self-help.
The right language for a contemporary prayer is the language a serious-minded person would use when addressing someone they deeply respect. Educated, careful, but not pretentious. Modern but not casual. Reverent without trying to sound ancient. You can find this register easily by reading the modern liturgies of your own tradition: the 1979 Episcopal Book of Common Prayer, the 2000 Common Worship of the Church of England, the modern Catholic missal. They are all written in this register because the people who write them have thought about it.
C. S. Lewis warned in his Letters to Malcolm that any prayer written in language meaningfully different from how the petitioner normally speaks introduces a layer of performance between them and God. He was right.
7. Don't claim authority you do not have
This last one is the difference between a traditional prayer and a modern one. A traditional prayer carries the weight of generations of Christians praying it. A new prayer cannot borrow that weight. What it can do is offer a careful piece of language for a specific moment, with the honesty that it is recent.
A new prayer should not pretend to be ancient, should not imitate Cranmer's archaic English, should not present itself as more than it is. It can be a genuinely helpful set of words for a specific situation. That is enough. The tradition has always allowed for it. Honesty about what it is keeps it inside the tradition rather than mistaking itself for something it is not.
What this looks like in practice
The next article in this cluster, Prayers for everyday moments, contains twelve editorial prayers written to these seven principles, each for a specific contemporary situation. They are short. They address God. They ask rather than demand. They stay within traditional Christian theology. They name concrete things. They use plain, dignified language. They do not pretend to be old.
You can write your own prayer using the same principles. The tradition leaves the words to you.