This is nice despite being extremely subjective ("know" is not something I'd apply to most of these things; "believe" is strong enough and correct), but some of them are questionable, and -- assuming the author didn't actually follow them in his younger years -- could've resulted in things being worse.

Prime example: If given the opportunity, people will surprise you. Leaving yourself open to these surprises is a kind of risk. Taking that risk is how you believe in people.

Yes, they certainly will, and yes, it's most definitely a risk. Unfortunately, that surprise, when it does come, is rarely good. Also, taking that risk too often can lead you to believe in people if you're lucky in your acquaintances; it can just as easily (if not more so) lead to the exact opposite if you're unlucky.