The other day I saw something interesting during my Logic class (yes, you heard that right, I have logic classes and they are actually fun). My teacher defined four types of cause to any object or event, and explained how these could help us better know said object (or event). Being a bit obsessive, I immediately tried to see if I could apply this to novel planning.
Now, I'm not saying this is how you should do it. I'm not even sure I will. It was a new way to look at things, however, and I think it's always helpful to test out new methods. You never know which will work better.
So here's a quick description of the four causes. I'm translating from French, so these might not be the exact, technical terms.
1) The Ultimate Cause: This is the goal. You can find it by asking 'Why?' Why was this thing built? Why did X event happen? It's also the most important, as it will influence the other causes.
2) The Material Cause: In a way, this is the nitty-gritty cause. It's the physical material you used, the stuff your object is made of. In the case of an event, it can also be the person who acted. So if you plan something and send minions to do it, the minions are part of the material cause.
3) The Formal Cause: This one is the plan behind your object or event, the way it's organised, the structure in it.
4) The Efficient Cause: This is the origine of your object. If it was built, it can be the maker. Sometimes it is also the person who makes the plan (the one who has the idea). The best way to find this cause is to ask "Where does the beginning of this thing start?" (No need to go all the way back to your world's Big Bang, though).
An example of this, from my work. The novel starts with Prince Heike ordering the assassination of his father, King Eckhart.
1. The Ultimate Cause: Grab Edingher's power. There are other motives for him to want that power, but the reason he orders the assassination is to have it.
2. The Material Cause:The dagger used for the assassination, and the assassin herself.
3. The Formal Cause: The strike's plan. There was a lot of planification involved in this assassination, and that is the formal cause.
4. The Efficient Cause: Prince Heike. This is his idea, and he is the one hiring assassins/planning the entire coup. Others are involved, but all of this starts with him.
Anyway, I hope that helps in one way or another. I try to do it with major plot points, and to be more exhaustive than above, because it helps me know what brought an event about.