Rule #5

Spend money wisely. Yeah, this kinda is a rule for life, but I've seen way too many kids my age spend ridiculous amounts of money on stuff. One of my friends this summer spent like $2500 in three weeks (or less...). Point is, unless you're the one using your own money, don't buy overly pointless stuff. Save it, and spend it on something hugely awesome later, rather than buying pointless crap now.