The steps in preparing sermons are easier to explain than they are to apply. Preparing good sermons requires deep personal wrestling. Fred Craddock, preaching professor from Candler, wrote to preachers, 'wrestle with a text like Jacob wrestled with the angel.'
I would add, keep wrestling until it blesses you. You will know it has blessed you, when something gets dislocated and you walk away limping.
CHOOSE A PASSAGE.
The best sermons usually find their anchoring point in a particular passage of scripture. Topical preaching can be done well, but for most new preachers, even topical preaching is helped by sticking close to a particular passage and bringing in other passages and supporting or clarifying material. If you use the lectionary, half the work is done for you. Just don't falsely force several lectionary texts together. If you use what Tom Long calls the 'Preacher's Choice' method, choose your text as early as possible. If you wait until that week to choose the text you are already behind.
READ THE PASSAGE THROUGH SEVERAL TIMES.
Say a prayer asking for illumination. Then read silently noting key words and relationships. Then read it out loud and see what reading it out loud changes in your perceptions. Take note of key words to explore, or any questions you need to ask. Define the boundaries of the text you will preach on. You don't want to preach the entire book of Isaiah in one sermon, after all.
BECOME PERSONALLY INTERESTED IN THE SCRIPTURE PASSAGE.
What grabs your attention? What issues do you have with the text? What unanswered questions are left hanging like loose shoe strings in your mind? What personal issues does this text touch on? The most interesting preacher is always the interested preacher.
CRITICALLY STUDY THE TEXT.
Using any bible study methods you may have in your repertoire explore: words in the original language, logical relationships between phrases, prepositions, what the text would mean if it used a different word, word pictures, metaphors, and images. Take note of those things that are interesting to you.
TALK ABOUT WHAT YOU FIND OUT LOUD.
Sermons are oral/aural things...we speak them and hear them. So it makes sense to prepare them out loud. Further, performance studies has reminded us in recent years that our whole bodies think along with our minds. So, let your voice, gestures, facial expressions, and whole body think about this passage. Find a quiet room where you can be noisy, or talk with a few friends or family members about the passage.
Of course I am using the word 'converted' broadly here. However, if you are truly interested in a passage, and if you truly search carefully and long enough for what it might want to say in its own terms, you will have a moment of conversion. It may come as an 'Aha' or a 'That's it!' or an 'I am undone.' Prayerfully ask this question: how does this passage change the way I live in the world this week? (Either thinking, acting, or feeling). How does this passage bring you the good news, news that convicts and frees at the same time?
PLAY WITH A SERMON FORM.
Sermons form best when they come together somewhat organically. Knowing sermon forms is helpful to a degree, since it gives you different patterns in your mind to try. Often, though, all that is needed is playing around with the introduction on paper or out loud. The primary goal is the take what was interesting to you, make it interesting to the congregation; then take what converted you, and help the congregation experience it, as well.
GIVE IT CONCRETE IMAGERY.
Use images from life as examples, metaphors, and illustrations to make the sermon more understandable and memorable. Examples are brief suggestions from real life that show rather than tell what the sermon is about. Metaphors are verbal creations where two unrelated images are pressed together: God is dew for example. Illustrations are usually reasoning by analogy and often end with, 'in the same way...'
The primary goal of this step is to help your congregation see this sermon on their street.
LISTEN TO REAL PEOPLE, AND REAL LIVES.
Get the sermon to this stage early enough that you are able to carry it with you through life for a while. How would this sermon sound to the people you visit, meet, and encounter: widow, teen, senior, laid off, grieving, dying, poor, rich, minority, or skeptic? Consider talking this passage over with someone from a different strand of the faith, and allow them to help you see it in new ways.
PREACH IT THROUGH UNTIL IT IS SMOOTH AND FAMILIAR.
Preach the sermon through out loud several times. If you need a manuscript, don't become confused and think of it as a sermon. Sermons are out loud events that cannot be fully captured on paper.
BONUS: Consider this quote on preaching from Karl Barth:
"If he answers the people's question but answers it as a man who has himself been questioned by God, then he speaks- the word of God...for being truly questioned by God and truly questioning about God, he will know God's answer and so be able to give it to the people, who with their question really want God's answer." ~ The Word of God and the Word of Man (sic)