Ally made a good point in her reply to my last post where she said it sometimes takes her three outlines to nail a story. I'm not sure if she means three entirely separate outlines or two revisions of her intial outline. I'm guessing that different writers have different approaches to outlining.
The method I tend to have used over the last few years is to bounce ideas around in a mind map. I create different threads for each character, thinking about who they are, how they behave and what they could within the story which would be fun or exciting or scary or whatever. Hopefully by this point I have a fairly good idea of the basic shape of the story.
Then I flip the page over and write out a scene-by-scene synopsis, adding or shedding ideas from the mind map as appropriate. With this first outline I'll try to strike a balance between brevity and detail. I'm trying to keep everything lean by only mentioning key details but at the same time I'll jot down vital pieces of dialogue, description, foreshadowing etc so I know where they occur in the story. And as I'm working in a 3-act structure I'm also figuring out where to drop the big bombshells that need to occur at the end of each act.
After reading through this outline I'll go through the adding/shedding process once more. Perhaps there are too many scenes at the beginning of the story, it's messing up the pacing. So I'll see if I can ditch some scenes or perhaps combine two scenes together so I'm still conveying the same amount of information to the reader but in a more succint manner. At this stage the outline will be much more stripped down than the first one as I've already established most of the fine detail. Whereas before I used several words to describe a scene, along with several arrows leading off to notes dealing with the embellishments, here I'm working in telegramese. "Fight. Gloating. Rescue" -- stuff that only makes sense to me.
Sometimes I nail it more or less straight away. Other times I have to polish the outline two, maybe threee times.
And sometimes the outline is more flexible than others. With the infamous "no headers" story due to time constraints I only did a bare bones outline and altered a lot of stuff as I went along. Setpieces would still be in the same place but often they weren't the setpieces I had planned.
And sometimes I don't even bother with writing an outline and just work out the whole thing in my head.