It's no secret that Harry Styles and his big sister Gemma are super close. During One Direction's many world tours, Gemma would often fly out to visit Harry and his bandmates — talk about a serious sibling perk! — and Harry has long been known to play the role of protective little brother. 

But there's so much more to Gemma than just her uber-famous fam. Style icon, accomplished writer and all-around coolest chick ever are just a few of the words we'd use to describe the newly-turned 25-year-old. And not all of us are lucky enough to have a big sister as awesome as Harry's sis. So, in honor of her monumental birthday, we've picked her brain and convinced her to share all of the best life hacks she's discovered along the way. (You're welcome.)

1. Good friends aren't determined on the length of time you've known them but the experiences you've shared.

2. Never make decisions on an empty stomach. You'll probably come across as meaner than you mean to be.

3. Phone insurance is worth the money.

4. People will always say mean things. When you feel like you can't win, remember they're the losers.

5. Don't leave the tap running while you brush your teeth.

6. Take your makeup off, then cleanse your skin...otherwise it's like showering with your clothes on.

7. You can cook potato waffles in the toaster. (This is an incredible latke-like breakfast food and one of Britain's greatest inventions.)

8. If your mum doesn't like your boyfriend or girlfriend, she's probably right about them. Sorry.

9. Travel as much as you can.

10. Get measured for your bras. Supporting the girls and wearing the right size will make your clothes hang better!

11. Switch your phone off at night (or use Do Not Disturb). Your sleep is more important than Twitter notifications.

12. Be happy when your friends become friends. Rather than worrying that you're going to be left out, embrace the way things unfold and you'll end up with an amazing group of people around you.

13. Revision is always better with colorful pens. (Revision = studying for exams in Brit speak.)

14. The book is always better than the film. Especially when it's Harry Potter.

15. Try not to get angry about things you can't do anything about. It's a waste of energy and the only person who'll be upset is you.

16. If you've never been taught it, then you won't know it. Don't feel bad about knowledge you're lacking and don't judge others for things they're not strong at either. Oh, and if you want to learn? Ask.

17. Buy decent jeans. They take longer to save up for but also last ten times longer and don't go saggy at the knees after two washes. Worth it.

18. Alternate which shoulder you carry your bag on or you'll end up lopsided. It's weird, but once you notice, it will drive you crazy.

19. Make playlists as well as photo albums. Collections of songs bring back memories in a whole different way.

20. Salt and vinegar chips are the cure for just about anything.

21. Don't save up your good candles. They look pretty on shelves but they smell even prettier.

22. In cases of a dress code panic, lean casual on clothes and dressier on makeup to cover most situations with ease. Black jeans plus a black t-shirt is my failsafe.

23. Own the basics to independent womanhood: a first aid kit, screwdrivers, and a hammer. (The first aid kid isn't necessarily intended for hammer related injuries...but two birds, one stone.)

24. Get dark-colored towels. They will withstand years of hair dye and fake tanning incidents.

25. Never, ever over-pluck your eyebrows. Get them done by a pro once every so often and keep up that shape at home.