15 lessons a man should have learned by age 30

I have something in common with Prince Harry: we both turn 30 this year. While he's been working tirelessly on the Invictus Games, I've been trying – and failing – to come to terms with waving goodbye to my twenties.

Here, to mark the tombstone – I mean milestone – of our 30th birthdays, are 15 life lessons that every man should know by the time he hits the big three oh.

1. How to cook a signature dish

No, "a mean beans on toast" does not count. You're 30 now, man – you need to have at least one dish in your arsenal with which to impress your friends.

Top tip: perfect the Sunday roast as its praise-to-difficulty ratio is stacked in your favour – people are disproportionately impressed by an ability to cut up potatoes and shove them in the oven.

2. Never try to replicate fun

We've all done it. You've been on an amazing holiday, or to an amazing party. Everything about it was perfect: the people, the location, the timing. So why not try to replicate it? You know, plan everything meticulously so it's exactly like it was before? Sadly, it's never the same – you always lose that wonderful frisson of unpredictability. By 30, you know just to cherish the memories.

3. It doesn't really matter what people think of you

Four words: you can't please everyone. Don't like the person I am, the person I've spent years cultivating? Bugger off, then. Goodbye forever.

4. Talking about university is boring

Ah uni, those were the days! Remember when you downed three pints back-to-back and everyone cheered? Remember when you turned up to a seminar having not been to bed, eyes wide like saucers? Enough already. Yes you had a fun at uni but, seriously, it was eight years ago! Time to move on.

5. It's easiest just to tell a girl you like her

God, it was tough. You'd go through it in your head over and over again: how do you tell someone that you like them? And what if she rejects you? That horrible humiliation; that crushing self-doubt. Yeah, all that has gone by 30. Like a girl? Just tell her. Life is short.

6. When to call it a night

It's 4am. You've just heard Everywhere by Fleetwood Mac for the second time tonight. The smell of desperation is beginning to pervade the room. Then someone says: "We need to get more booze." "Great idea!" comes the response. Except it's not; it never is.

7. How to choose a good wine

You don't need to be able to witter on pretentiously about the grape's integrity, but you should by now be able to remain unflustered and pick a tasty wine when faced with a snooty waiter and a menu longer than War and Peace.

8. Fancy dress isn't all about offending others

The party invitation says "fancy-dress". What do you do? You probably want something fancy, funny and maybe a bit provocative. Fine. Then some guy thinks he's being edgy rocking up in a bin Laden outfit. "Look how shocking I am," he thinks to himself. Thirty-year-olds look at him and think: "what an attention-seeking prat".

9. How to change a flat tyre

You're 30 now; it's time you acquired some practical skills. See also: putting up bookshelves and performing basic home repairs. (Confession: I am yet to change a flat tyre.)

10. Friends getting engaged is a happy occasion

I know, I know: you should always be happy when your mates get engaged. But come on: when you were 25, your first thought was, "well, there goes our friendship." Am I right or am I right? Now, though, you're the first to "like" their Facebook announcement and marvel at the beauty of their love. Maybe.

11. Have a signature aftershave

Aftershave is one of those things you can never really buy for yourself. It's a birthday present from your mum or a Christmas gift from your godmother. Maybe you'll get some for Valentine's Day. Make it easier for everyone, then: stick to one scent.

12. Glamp it up at festivals

Sharing a small tent for five days with nothing but baby wipes to cleanse you may have been OK when you were younger, but now, now you want more from your festivalling experience. The answer is simple: glamping. Clean toilets, nice shower in the morning, spacious living quarters: yep, that's the way to do it.

13. How to drink the whole day

If there's one thing the quarter-life onslaught of weddings teaches, it's how to start drinking at midday and carry on going until long after dark. No 30-year-old, then, should ever get so blindingly drunk that he has to go home before dinner is served.

14. Alfred Hitchcock's back catalogue

It should be made a law that everyone watch Alfred 'The Master of Suspense' Hitchcock's entire oeuvre by the time they reach 30. OK, maybe not all his work – there are 52 surviving films – but certainly Vertigo, North by Northwest, Rear Window, Psycho and Strangers on a Train. Each and every one is a ripping yarn that will provide you with ample input should the 'what's the best film ever made' conversation come up in the pub.

15. What happens in the bedroom stays in the bedroom

Maybe there was a time when you'd regale your friends down the pub with stories of your glorious sexcapades, rejoicing in every salacious detail possible. Not any more. By the time you're 30, almost anyone you share an intimate moment with stands a chance of becoming your lifelong partner. And the last thing you want is for your mates to know about the bedroom predilections of your own wife.