I don't know who needs to hear this, but your save doesn't have to be "perfect".

@Astro Having a general idea isn't bad! If you go in not knowing what you want to do it all, you'll get bored anyway. But a lot of frustration and boredom also often comes from being unable to roll with the things the game throws at you, I think.

And as for aging, I don't think it has that much impact on normal gameplay, anyway - it just helps you play at a pace you're comfortable with. If you get bored of the same Sims quickly, play on Short. If you want to spend more time with them to get attached to them, pick Normal or Long. There's something for everyone. :)