Many people say they don't pray because they don't know how. They're happy to step aside and let other people do it for them. But judging by some tortured efforts at prayer I have heard, out loud, in public, and from the heart, many of these folks find themselves in situations where they have to do it anyway. You never know when it might happen to you—when you might find a microphone thrust into your hands and be asked to open a meeting, or a ball game, or a locker room pep talk, or a family reunion, with a word of prayer. Here are some tips that I hope will help.
DO set your thoughts in order before you open your mouth. You can even jot down some notes, even a word-for-word manuscript if you wish, and if time permits. Regardless of some people's prejudices against premeditated prayer (as opposed to praying "from the heart"), there is no law against praying even a prayer written by someone else, or one that you rehearsed ahead of time, or one learned by heart and used again and again. After all, the Lord's Prayer is precisely how Jesus instructed his disciples to pray. Provided that you read, recite, or extemporize your prayer with attention to its meaning, it is probably an improvement on the long-winded, rambling, repetitive, and sometimes painfully awkward prayers that often result when a speaker goes into prayer mode unprepared.
DO be clear about what God you are praying to. Don't let the presence of people of other denominations or religions scare you into being vague and wishy-washy about the recipient of your prayer, any more than you would soft-pedal the fact that God exists out of consideration for agnostics and atheists in the house. Stand up for what you stand for. Direct your spiritual letter in such a way that it will arrive at the correct address, and let no one hearing it be confused about whom you are addressing. It is better to take the heat for sounding a clear signal that upsets some armchair general, than to make an indefinite sound that no one can follow. Just because the Spirit "helps in our weakness" and whatnot (Romans 8) does not mean we should let our theology slip when we pray.
DO show respect and humility when you speak to God, especially in front of other people. Affecting a buddy-buddy relationship with Jesus, or worse, a type of romantic involvement with him, isn't in good taste. You wouldn't use a pet name to address a judge in the open court, or a professor in the packed lecture hall, or a general in front of his troops, even if you were on intimate terms with him. Remember who you are, and how unequal you are with God, and how much you depend on His undeserved favor, and the fact that you're no better than any of your listeners; then, if you're still not sure where you stand, imagine that someone else in the room was leading the prayer and show God at least as much respect you would demand of them.
DO mention your rationale for asking God to hear your specific request. This is a good place to stick Bible verses into your prayer (another way that it helps to be prepared). It isn't so much that God needs to be convinced, as that sometimes you and other people listening in need help believing that such a prayer will be accepted by God. Remind yourself, and them, that it is in God's character, expressed by the salvation history recorded in Scripture, to do the very thing we now ask of him. This is how, without having an axe to grind, you can use the time of prayer to instruct the people and strengthen their faith. Prayer is, after all, an exercise of faith.
DO end your prayer with some sort of doxology. It has to end somehow. It might as well be to the glory of God. A well turned doxology is an excellent way to cue the crowd to say Amen. In a certain sense, it's another way of saying Amen. Which is to say, "This is true," or "So we believe," or simply, "We trust You."
DO let the people say Amen. It's not as if they have too much to do. If they don't come right in on cue, give them a gentle prompt, such as: "Let the people say..."
DO listen to yourself—if possible, by playing back a recording of the event where you prayed. Notice your awkward and tedious mannerisms and make a conscious effort to correct them the next time. Listen for sentence fragments, thoughts that went astray, repetitions, cliches, meaningless platitudes, embarrassing gaffes (even ones you're sure no one else noticed), inordinate amounts of throat-clearing, hemming and hawing, fancy rhetoric and complex grammar that most likely went over the people's heads. Then reconsider how much time you could and should spend preparing when you are next called on to pray.
DON'T be a pompous bore. While it's OK to pray in King James Bible language, don't lay it on any thicker than you need to. Having a stained glass voice isn't as important as directing the people's faith toward God's blessings, like a beggar's hand opening to receive alms.
DON'T make yourself conspicuous by your wit, eloquence, or charisma. Use it to the glory of God, for the building-up of the brethren. You aren't supposed to be on display. You're supposed to be a spiritual telephone for God's people to talk to Him. Try not to stand in the way.
DON'T assert anything that you can't defend based on God's Word, and don't demand anything of Him that He has not promised. Remember that "Thy will be done" comes before "Give us our daily bread" in the prayer Jesus taught us to pray. Remember that the church has always been, and still is, a refuge for the poor, sick, troubled, grieving, aged, and dying. If you pray in a way that suggests that health, wealth, youth, a happy family, and other gifts are unfailing signs of being right with God, you bear false witness against Him and the suffering faithful. Also remember that these outward signs of God's blessing have often concealed hypocrites who brought shame and scandal to the church.
DON'T string together too many clauses before coming to a full stop. Try using shorter sentences, and make one point at a time. A rule of thumb: If you can't remember which Person of the Trinity you were addressing at the start of the petition, you're probably doing it wrong.
DON'T fall back on trendy catch-phrases to fill moments when your mouth has run ahead of your brain. If you feel a litany of Lord, we just want to thank yous, Father Gods, sweet Jesuses, and what-not, bite your tongue. Saying nothing for a few seconds wouldn't be any worse than chucking in a piece of thoughtless blab. Listen to someone who often falls into these traps when praying, and you'll be amazed that they can be so ritualistic in their "from the heart" prayer while condemning you for preparing ahead. Bottom line, think before you speak—even to God. He deserves that much, at least.
DO name names. Don't just pray for people in general, or for so-and-so's relative or acquaintance. If someone among us, or close to us, or even a public figure has an illness, or an operation, or some other problem, we should certainly intercede for him or her by name. Even a list of names—"Christian" names are enough—added to a general petition for the hungry, sick, recuperating, etc., can make a general case so concrete and specific that the people will feel the difference prayer makes. We're not just entrusting all needs to God; we're putting our needs in His hands.
DO read written prayers, such as collects, litanies, and general prayers, at least from time to time. You can learn a lot from them about what to pray for and how to structure your thoughts.