I think if you have a backstory for your sims, or give them more of a personality, then you can make decisions about their actions based on what they would logically do, like someone else on here suggested. I like to cheat reward traits and skills when I make a sim, just to give them more of a personality to start off with. It also helps to get trait and aspiration cc so you have more variety in your sims.
Here are some backstories for my current sims. Feel free to use them for your own gameplay.
--Guy who was born poor but now has money and owns multiple businesses. He likes to drink, fight, gamble, party, and womanize. He doesn't plan on getting married until late in life, if at all. And he doesn't plan on being faithful.
--Mother of teen and young adult children who wants to interfere in their love life and find her children romantic matches. Her goal is to marry them all off and have big weddings that will make her friends jealous.
--Musical prodigy who has relegated music to the sidelines as a hobby in favor of being practical and following in the footsteps of his father's business.
--Employee who's in love with the boss' daughter and secretly reads her journal. He has a girlfriend, but he never lets her get that close because of his obsessive crush on the other woman.
--Quiet and kind artist who likes to take walks and paint nature. He has chronic pain but tries to mask it. He just wants to settle down and lead a quiet life.
--Girl whose family expects her to pursue ladylike hobbies, get married, and have kids. But she's a tomboy who likes to collect rocks and craves adventure.
--Girl who went from riches to rags and is unsatisfied with her job. She's looking for a rich husband so she can regain her wealthy status.