I’m not the person you’re replying to but I have a fun answer for how I did it before I moved to password managers.

I used to have just a single password, normal-ish password. Reasonable length, some numbers in there, random caps. But in order for me to have unique passwords on every site without losing track of all the unique password, I added the first and last letter of the name of the service at a specific point inside the password. My password was cryptic enough that if you would see it you wouldn’t immediately notice it. But for me it meant I had a single strong password that was easy to remember and unique for every service.

I’m still kind of proud of that one, even though I don’t use that method anymore.