I plan like a mofo. (Except Kim's story, where I just wrote and wrote and ended when she died. Even in her story, I had a rough outline because it occurs (on top of / simultaneously with) other stories. That is, I knew before writing which major events were going to occur... I just didn't know yet how she would respond to them.)
My outlining strategies will be pretty useless to you since I try to make one character dominant and everyone else side-show. My result is that usually one character carries the canvas and everyone else gets to reach in and paint their own strokes.
All disclaimers aside, I start with the simplest possible description. ONE verb if possible. Never more than three verbs. I expand outwards from there in 3's. So column (B) in the spreadsheet = the major arcs and column (C) represents the sub arcs.
For example, in a recent story "Woman learns too late the wages of sin" I have 3 arcs:
1. Evil at the start
2. Change of heart
3. Retribution
Each of these arcs turns into 3 arcs which turn into 3 arcs each and so forth until I can't break it down any further.
Here: 3 nodes deep:

No big shocker, I picked three sins. Avarice, Mendacity, and Passion (Anger). Original intent was to go through each (in the style of Dickens 3 ghosts), but that didn't pan out , and all those nodes got culled.
The middle "Change of heart" story arc, explored one node deeper:

Anything that breaks the rule of 3's gets pruned until it does. If it can't be reduced, I sit down and ask myself some hard questions about the story. Is the story trying to accomplish too much? Is it too complex? What story am I trying to tell?
Right now, my scientist character (Marsha) faces those questions. She's the 4th strand in many nodes. Should she get her own (more structurally sound) story? Is she helping the current story or is she hindering it? I seesaw on this every day. She passes the relevancy test, but not the rules of 3. Difficult choice!
Btw, beyond the 3rd tier of branches, I rarely stick to my outline. Characters surprise me and make weird decisions. Sometimes reviewers go "hey, J can't kill her sister in cold blood. It's repulsive. I hope you can change it" and I'm looking at my sheets and it's like level M down the chain and not crucial to A, B, or C so ya, outline can go fly a kite.
Coming back to yours... if you decide to approach such a strategy, I recommend you lay out all your bullet points. Make a giant shopping list of all you'd like to happen. Then go through and split into two columns (A) cause and (B) effect. Some items will be sitting in "effect" with no apparent "cause". That's normal. Then, go through your causes and see if you can link them to a new column which is the greater causes. At this point, some of your orphaned effects will now join up. After several passes, you may be 3-4 nodes deep, but everything will join up. Anything that doesn't join up needs close scrutiny.