Throughout your life, you will receive a lot of advice. Some of it, you will hear from a lot of different sources. Some of it, you will probably hear only from me.
Never dress yourself in the dark. No matter how much time you think it will save you not to turn the light on, you stand a chance of looking completely ridiculous, and you won't realize it until it's too late to do anything about it. (Some more general advice might be to get a good look at yourself in the mirror before leaving the house.)
Don't do the drugs that make you lose your friends and furniture. This is one I heard as a harm reduction volunteer. There are a lot of drugs out there to experiment with, use, and abuse, and the popular propaganda about drugs makes it seem like each one is just as bad as the other. Nobody ever went completely broke because of their magic mushroom habit, though. So, if you're the sort who likes to experiment with drugs, it might be prudent to stay away from things like meth, coke, and heroin, since they carry a higher likelihood of ruining your life.
Never trade a crack addiction for a meth addiction. I first heard this advice from a former trance DJ in Seattle. The way he explained it was, "Yes, it's cheaper, and yes, it lasts longer, but trust me, it's not a good idea." More scientifically speaking, meth makes you impulsive (among other things). Drug addicts are known for doing just about anything to get their next fix. Meth addicts will do just about anything for no damn reason.