Tips for making an Ultimate Sim?

Whether it's the game mechanics or not, I find that there is no template for creating an engaging sim--because regardless of traits/skills/careers/families, all sims tend to act pretty similarly. I think finding a sim engaging is directly proportional to how much you pour into the sim--if you play them and acknowledge their experiences and traits, then you'll find them more animated and complex. That being said, OshinSims on YouTube has several videos on how to create more interesting sims. Her ideas and practices have been very helpful for my gameplay.