Jenni, that's a good question. I guess in the past it might have been long over lean (if you go by silhouette) or a dress/ skirt outfit.
Another way of thinking of your formula (if you have one) might be eclectic/ interesting shoe plus -- whatever!
I do think you like to include several items with significant detailing in them, so maybe your shoe and a patterned pant or top or a top with some textural interest. That might count as some kind of formula.
I guess even that old mantra: colour/ pattern/ texture/ shine might be a formula of sorts.
Hmmm. It's tricky, right?
I feel like you -- I don't think I have a formula. -- i just get up in the morning and put on what feels best -- but then again, I do tend to wear a few core silhouettes, as Jonesy said she does. The silhouettes do vary over time (in my case) because I like to play with proportions more than colour. I stick with a fairly limited palette.