A little bit late to this very interesting thread!
I usually mentally put my outfit together during my morning shower. Centered around one favorite piece, and the rest to go with it. I also noted the outfit, on an Excel spreadsheet at work. Very illuminating over time. Helped me to remember what outfits or individual items did not add happiness, and which were super combinations (as well as tracking wears).
I am not a big accessories person in terms of a lot of jewelry choices or shoe styles. I usually wore the exact same earrings and necklace (simple gold chain w/heart) every day, and the same style of shoe (if not the exact same shoe) every day. Plus I keep a bit of a limited color palette, and I do try, when shopping, to make sure new things will "go" with other things.
I did try to spend time with new purchases to try out combinations in advance - after work, while still wearing the proper undergarments & stockings, or right when I brought the new items home
I also tend to be a bit obsessive over a few items at any one time, so those would get high rotation, and I never care about repeating! I did catch myself repeating my casual Friday outfits a lot!
But of course there would be mornings of frustration, especially when introducing a new piece or combination. I only had a little bit of time to goof around with changes, and sometimes had to shrug my shoulders and mentally tough it out for the day. I've had plenty of "fails!"