This is probably a question most pastors have had to answer at some point in time. It is also a question pastors often ask each other. I just recently sat down with a dear brother in Christ who is a pastor about an hour south of our church. Sermon preparation is one of the skills every pastor must sharpen, even seasoned pastors. I have been preaching for 11 years and on an every Sunday basis for the last five years. Sermon preparation for me has changed over the years, but here is a basic outline of how I prepare on a weekly basis:
Prayer: Prayer must be the fuel for sermon preparation. There is an obvious difference I have noticed in both the sermon preparation and delivery when it comes to prayer (or the lack thereof). We are given the great privilege of preaching the Bible and are unable apart from the Spirit of God to correctly understand and convey it's message (See 1 Corinthians 2). Prayer must come before, during, and after sermon preparation.
Read the text: For the last five years, I have preached through books of the Bible. In five years, we've gone through the book of Job, Titus, Esther, Galatians, Jonah, Mark, and will be finishing up Genesis in a few more weeks. I am thoroughly convinced, while preaching through books of the Bible is not the only way, it is the best way. It allows you to work through narrative and arguments in a natural way. As a storyteller, my favorite part is allowing the story/text to unfold and reveal itself. For the first day, it is important to read the text over and over (usually up to three times), including the surrounding context to refresh the mind.
Write out personal observations: I am a little old school when it comes to using technology in sermon prep. Some guys are really amazing with tools like Evernote, Notability, and countless other ones. I use a legal pad and pen. As I read through the text, I ask questions and write observations. Nothing fancy. The goal of this part is not to come up with some catchy alliteration or produce an outline of what I see in the text. The goal of this part is to get at, "What is the author trying to convey? What does it mean in it's immediate context? What is being repeated in the text? What are the implications of the text? Where is Jesus in all of this?" Verse by verse, paragraph by paragraph, I write out all observations and questions.
Commentaries and books: After writing out observations and questions, I check my observations and answer as many questions with trusted resources. Men, the reality is there are a million resources out there. You can spend a whole day just digging into commentaries, blogs, articles, Bible software (highly recommend Logos), books, and other resources. I have a few trusted resources I go to. For good Bible notes, I use the ESV Study Bible. For a good commentary, I use the MacArthur series and the Preach the Word series by Pastor R. Kent Hughes. For good books, I use John Calvin's Institutes of the Christian Religion and more specific books according to the text I am preaching. The purpose for reading commentaries and books is to check what you've already observed. Sometimes I realize I was spot on and other times way off. There are sometimes I've noticed things that were not written about in the commentaries I've checked (which could be good or bad). The point is we sit on so many resources of faithful men and women who devoted themselves to the study of God's Word. Don't forget to thank the Lord for these men and women.
Outline: After looking at my notes and checking them against commentaries, I try to come out with a creative and communicable outline if it is there. I will be honest, creative titles and alliterations are not my gift (For instance, our sermon series on Genesis is called Genesis. Brilliant. I know.). However, if I can make it memorable I do my best to boil the sermon to a simple, succinct sentence (there's an alliteration!) I call the big idea. As an example,
Rough Draft: The rough draft focuses mainly on the body of the sermon. I write out a full manuscript (I will do a blog post on why I choose this method vs. rough outline or no notes). I have a color coding system for my notes that looks like this...Green is sermon text. Blue is questions I am looking for answers (rhetorical questions are left blank). Yellow is main points. Orange is cross reference text.
Run it by Someone: Usually this person is my wife. Sometimes I run the sermon by some guys I'm discipling. I always run it by my friend, Daniel. He's hilarious and helps me bring out the humor of the text (something I will be writing a blogpost about). This is always a helpful time because it shows if I am writing and communicating in a way that is understandable and, more importantly, faithful to the text.
Final Draft: The final parts of the sermon I write are the introduction and conclusion. My introductions consist typically of a question leading into the big idea. For instance, if the big idea is "Following Jesus requires us to be unquestionably generous," then I'll begin the sermon asking, "Have you ever been on the receiving end of someone being generous?" I may share a short story, but I limit the introduction to a few minutes. The conclusion always consists of application and Christological connection.
Don't look at it: Friday is my family day. I don't think about the sermon, the text, or Sunday at all. It doesn't mean I don't pray or have random thoughts. The point is to give me one day away from the text and let the absence make the heart grow fonder. I know it sounds dumb, but it works for me.
Print and pray: On Saturday evening, I read over the sermon manuscript, make any necessary changes or adjustments (usually to illustrations, introductions, or conclusions). Rarely do I ever find at this point a need to change what I've written about the text unless after reading the manuscript over I realize I am way off on the intended meaning of the text. I print and then pray over it asking the Lord to be glorified in the preaching of His Word.
Pray some more: Our worship team comes together and we pray over the entire worship gathering, including the sermon. It is always a blessing to have others pray for you, especially those serving alongside you.
In total, this is about 10-15 hours a week. I realize some pastors need more time and others need less (my friend, Ryan Huguley, is writing a book on how he does it in 8...can't wait to read it!). When I first started writing sermons, it would take me sometimes 20-25 hours. Here's my advise, take as much time as you need to faithfully study, exegete, and explain the text. The more disciplined you become, the less time it will take you. This is how I prepare and write sermons.