Interesting to compare notes with others keeping plant records. My spreadsheet is less comprehensive than some, but here are one or two things I include which have not been mentioned so far:
If a plant dies, I change the colour of the row to red. This way I keep track of it and if I get a replacement, I change the colour back to black.
Likewise, if I plant any spare seedlings directly into the open ground (as well as potting some up), I colour the row green. It is easier then to keep track of them (particularly after a winter when I have forgotten all about them) to see whether they have establised or not. If they have, then I change the colour to black.
I also number my beds (mentally) and have a column for recording the bed number a plant is put in. When I have forgotten a plant’s name (frequently!) this helps to locate it from the spreadsheet especially if its label has got lost/faded/overgrown.
If I go to a Nursery or Show, I take a print-out of my spreadsheet. It helps to avoid buying a plant you later discover you already have!
Finally, when I moved house, I left a spreadsheet print-out behind for the new owners (SRGC members) and started a fresh one for my new garden. The old one is useful for reminding me of plant names I have long since forgotten and has helped me to help the friends in my old house when they come asking for and ID of any plants they inherited for which they can’t find the name.
