During my study I write out the flow of my sermon. Then, from that rough draft, I write out notes to take into the pulpit. I usually have about ten half-sheets of notes for each message. I have everything written out that I want to cover. I have some statements written exactly the way I want to phrase them. Certain truths need to be stated accurately or in fresh terms, so that I am not misunderstood or repetitious.
Since I preach in the same church week after week, I do not want to phrase the same truths in exactly the same way time after time. To keep my messages new, I need to guard against falling back into habitual ways of saying things. Extensive notes help me avoid that. They also assure that I do not forget something important I wanted to say. Since I use many cross-references, I need to write down their chapter and verse as well.
My notes are the record of my study of a passage, so I try to make them thorough. If they are too cryptic, I will not remember my flow of thought later when I review them. For example, if my notes say, "Tell story of boy and dog," six months later I may not remember what boy and what dog. Even referring to an Old Testament story requires some notes, so I can recall later what nuance of that story was relevant.
I am also writing a commentary series on the entire New Testament. Sometimes the commentary on a book is written several years after I have preached through the book. My notes need to have enough of my exegesis to reflect how I interpreted a passage for the sake of this later use.
I am not really bound to my notes when I preach. I do not read a manuscript. On Saturday evening (or Sunday afternoon for the Sunday-evening message) I read through my notes and highlight key points with a red pen. These red notations are a visual crutch if I need them. I have learned through experience how to look at my notes while I am preaching without it being obvious to the congregation. I could preach my sermons without my notes. I might forget a few things, or not say something exactly the way I wanted to, but the main thrust of my message would be there.