Single sim and money cheat down to zero. Even doing it that way, the game unfortunately is not all that challenging. I usually don't like dealing with children as they are even more annoying and less productive than adult sims. Sometimes i'll limit myself as to how I can make money, what I need to do before I can invite someone to live with me(it's highly unrealistic that someone would just move onto an empty lot with you), and don't accept any outside funds(people moving in). I basically play the same way in 3 and 4. 3 can be tougher with seasons as you need to get a home before winter.