Since turning 30, I've learned a couple of things.
Should you ever meet the man/woman of your dreams (and I hope you do), hang on to that person with every bit of love that you have in your heart. Do your utmost to make them feel special. Exercise and appreciate your responsibility as one half of something really unique.
Don't go out on a complete bender just because it's your friends birthday, stay out all night and not call, but when you eventually do (from a pub), be a complete cunt about it. Don't feel sorry for yourself when they finally get sick of your behaviour and walk out. Don't break down crying in front of their mother, begging to be forgiven for behaving like an idiot.
Don't fuck it up the way so many other people do.