You should try a random challenge one day. I did that a lot and it was actually very rewarding as it made me try things I would never normally do with my sims. Make one sim, completely randomize their looks (you can adjust hairstyle, makeup, clothes, etc.) and then randomize their traits. Try to only do things according to their traits, wishes, and basic needs, and see how it plays out! (also, to make sure they mutliply, try for baby whenever they want to woo-hoo)