Always look on the bright side of life.

Don't care so much what other people think of you.

You regret the shots you didn't take more than the ones you took, just go for it.

"Don't be an asshole. The world doesn't revolve around you. Also, that means minding your own business. If it's not hurting you, then it ain't your business."

Since winter is coming: don't eat yellow snow.

More seriously, do NOT live day by day. Nothing ever changes, nothing gets done, unless you plan ahead.

While I don't necessarily think people have to be strict about abstinence, this advice is still a good one...

"Keep your genes in your jeans." 

Life doesn't end after 30. We as a society tend to act as though you're "old" and "over the hill" once you get to your 30s and 40s which is nonsense. Many people didn't find their calling or achieve their goals until later in life. It's never too late to turn over a new leaf.

Hell, take my avatar; Godzilla didn't win his first Oscar until he was 69 and had starred in 36 films! ;)