I'm a terrible rotational player, too, and never even really tried as a kid. I just made my family and stuck to them forever. And because I hated rotating families, I would just make everyone from the family live together until death. That means grandma and grandpa had to go before I had any new kids. I preferred doing it this way simply because I'm terrible at keeping track of time in the Sims. If I'm having fun in a Sim game, I won't notice how many days I've played, or how many seasons went by. It's just a lot of math to deal with that my brain just doesn't.
However, I've recently started getting back into Sims 2, and really wanna give rotational play a chance. I just have to get a system going, which will most likely be some usage of WordPad. I am also thinking of using the Neighborhood stories as a way to keep the neighborhood updated for me. If I run off to rotate a few families and come back to the first, I'll end up forgetting what I was even doing with them to begin with. But the neighborhood stories will help me keep track of my thoughts, which makes setting up my Sims' stories a whole lot easier.
I plan on doing this with the premades in Pleasantview first. Too bad I do not have the patience to make my own neighborhood from the ground up, or I totally would. But that's a lot of work for me that I'm not willing to do. Maybe eventually, after I've gotten used to rotational play lol
So my TL;DR advice? Notes and Neighborhood stories. Also, weekly play. A week in Sim time gives you a little time to play around and have fun with the family before switching to another.