Write it down!
Because no matter how convinced you are you will remember, you probably won't.
Brought to you by me scrabbling around trying to work out what needle size I had used on a pattern.
I have picked a shiny new notebook (because we all love stationery) to have as my "sits next to the sofa for making design scribbles" book. Because writing random notes on post-its is only marginally more successful than not writing it down at all.
Let's see if I can take my own advice.