What informal rules did you learn when you were younger, that still tend to influence your behaviour or outlook today? I ask specifically of rules that you learned or that were revealed to you through experience, not through formal lessons.
Here are some of mine…
Hurrying a task does not get it done faster, unless you are very organized.
You can’t run away from problems. [sub]Even though I still try…[/sub]
You shouldn’t go out with the ex of anyone you know.
You shouldn’t rent from anyone you know.
Intelligence is much less important in the working world than social skills and willpower.
Despite all protest to the contrary, your style of dress and your car do matter.
One’s personal art doesn’t pay the bills.
If you’re about to be talked into something, and your intuition is screaming, No! Don’t do it!, follow your intuition.
You shouldn’t go out with anyone significantly older or younger than yourself.
The only reliable way to meet people is to be thrown together in the same environment (school or work, for example) for some time. You will be rejected if you simply start speaking to a stranger.
<in my experience>
You won’t get the chance to go out with anyone richer, more gorgeous, or more famous than you; money and image will always be more important than love and friendship.
You also won’t get the chance to go out with anyone from another culture; family objections will prove more important and lasting than cross-cultural interest.
</in my experience>