1. Brainstorm from January-November
Every pastor knows his church and ought to be able to anticipate some of its needs. In addition, there are certain books, passages, and subjects that pastors come across they want to preach. For eleven months out of the year, I jot as many of these down as I can. If I am leading toward preaching through a lengthy book (like Genesis or Romans) I try to think through how to do so. Maybe it would be best to preach, for example, Genesis 1-11 and then take a short break and pick up in chapter 12 or maybe it would just be best to start in Romans 1:1 and continue until you finish.
Also contemplate on what sort of doctrines and topics you would like to preach. Topics might include marriage, money, faith, temptation, the fruits of the spirit, grace, the cross, and on and on. Doctrines might include the atonement, theology proper, eschatology, etc. Consider the logistics, invest in resources, and take any notes or ideas you have.
2. Write Out Every Sunday and Mark Every Holiday and Special Services
After brainstorming for eleven months, I get out my calendar and write down every Sunday of the next year and then mark every important holiday or special service that might call for a unique sermon. These include Resurrection Sunday, Christmas (which might be a series), Mother's Day, and Father's Day. Some add Sanctity of Life Sunday, New Years, Independence Day, and special occasions.
In addition to these, if possible, mark the days you plan on being on vacation. My church blesses me with two paid Sunday's off each year. I work with my wife to plan these Sunday's out. One year she was pregnant and so we knew to reserve a Sunday around the end of the pregnancy so I could better serve her and our growing family. Other years I was taking summer courses in seminary and so reserved at least one Sunday for that.
3. Seek to Preach Variety
For me, I prefer to preach a variety of books, texts, subjects, etc. For example, I like to begin each year digging in the life of Jesus. So from the first Sunday of the year to Resurrection Sunday, I walk our congregation through the ministry of Jesus. For the past few years, this has meant walking verse by verse through the Gospel of Mark. I know right now that I will begin next year in Mark 4:1 where I left off last year.
I also like to preach from the Old Testament. I have preached from both short minor prophets (like Haggai and Jonah) and lengthier historical writings (like Exodus). I always try to make sure our people are exposed to the Old Testament.
In addition to an Old Testament book I seek to cover a New Testament book. So far I've done Philemon, Jude, Colossians, Philippians, Galatians, and others.
I usually pick at least one subject. One year I preached on temptation using Dr. Russell Moore's book Tempted and Tried as my inspiration (other than the Bible of course). I've done faith, the fruits of the spirit, marriage, and other subjects.
I always seek to preach at least one doctrinal series. Our churches are suffering with a lack of doctrinal depth and I do not want to forsake preaching the truth of orthodoxy. The key here is to show your congregation the truth and its application. Over the years I have preached on Theology Proper, Christology, the atonement, ecclesiology, and eschatology.
Finally, I always try to do at least a small series for Christmas. Sometimes its just a two-part series. Sometimes its more.
The above is only a guide. If I am preaching through a lengthy book, I will have to sacrifice one or more of the above. If I am preaching through Romans, for example, I might hold off on a doctrinal series knowing that one cannot avoid preaching doctrine when preaching through Romans.
4. Plan Your Preaching
Now you can plan your preaching. I read through Mark, for example, and meditate on where to begin a passage and where to end. From there I trace it through Easter.I then contemplate on how many weeks it will take to exposit through this or that book, how many weeks I'll spend on this or that doctrine, etc.
5. Be Open to the Spirit
This is a practical guide for the pastor, but the ultimate lead should be that of the Spirit. You know your people but God knows them better. You are their pastor and are called to shepherd them. This might, at times, require an interruption of a series or a changing of your planned sermons. That's ok. Events pop up in the culture and in the congregation that the man of God is commanded to address. Don't be a slave to your preaching calendar. Be a slave of Christ in whom you proclaim.