GrumpyNana:
Did I understand correctly? You have a spread sheet system already? Any pointers, thoughts, tips?
I do use one. Year per page. Title, start date (if it's a film I write film in that column), finish date, might i want to rewatch (yes, no, meh, sweary no, or 2nd if it is a rewatch), year aired, country, genre. And then I made some columns for director, screenwriters, source (like novel author) - those were easy to fill in when I was transferring my first year data over from MDL but unless I remember some of it I tend not to look it up. I'm mostly using those columns now for things like urls on indie productions that might be hard to find again. And a final column for actors, though that's not useful for sorting so it's more of a memory aid and moment to appreciate the actors I liked in it. (This is easier with Thai than some other countries.)
MDL not having an option to look at a year's viewing is a big reason why I started it in early January. I like being able to say this was my first year, my second year, and see how my tastes and explorations have changed.
I also have reminders at the bottom for a few series I'd like to watch or rewatch so I don't have to go back to MDL to remind myself of the name every time because I'm liable to get distracted. My memory is old too. And my PTW is a black hole of good intentions :)
So my tip would be, just start and see how you use it. If you want more or less, you can add it in or delete it later. Whatever you want, in the order you want it.