Posting to r/photography might be a good idea as well.
In terms of online storage, I use One Drive. I’ve used Google One and Flickr before. You’re welcome to stick to iCloud. Off the bat, UI is probably the most important thing and finding one that works for you is key.
Format wise, I’ve done Year->Month->Date and Categories (Landscape, Portraits, etc).
Whichever one makes the most sense to you is how you should structure it. I’ve stuck with Year->Month->Event within the month if applicable (Weddings, friend’s bday, etc)
This is my logic coming as a hobbyist photographer. A professional/business photographer might have a different workflow. I can imagine professional sorting by assignments.