tracker sites are the easiest, MAL, Anilist, manga-updates, if you wanna take it a step further then making a spreadsheet would be helpful (I do the ladder)
You just need to have marked or tags
Rate everything and giving them tags when you save them seems to be the best possible way if you dont want to take screenshots pr save to another site
latter**
Can I make it (only visible for myself) or should I make it share in timeline?
Whichever is fine i think
What should I do so if my lists got deleted in the future I would still know the things I used to have in?
Yeah I know I'm a bit late but I'm scared it would happen again