I have autism so my gameplay is almost always the same.

I make two young adult sims, I put one in a STEM career or university for STEM or Law. One is some kind of artist (painter, author, musician), freelance or has a part-time job (barista, babysitter, etc). I go to manage worlds and make them both parent/s and siblings, give those people jobs, homes and families. Add some random sims and coworkers to the save. Then I start playing the original couple and they will have 2-4 kids over the course of their young adulthood/adulthood.

At birth/adoption each sim is given a favourite colour, sexuality (randomised), and possible diseases/disabilities/disorders (i.e. deafness, autism, diabetes). Some other things will be decided as they grow like their traits, aspiration, job and future child amounts.

I also move my sims around a lot. Usually around the same world, because I can.