We parade through our teenage years with absolutely no idea what we're doing. Fake it till you make it, I always say. Even when we turn 18, as legal adults, we can still kind of get away with frolicking through life without much regard for ourselves or our surroundings. But by the time you reach the end of your second decade, it's time to put on your big girl pants because there some things that you just have to know how to do with no exceptions.

By the time you turn 20 years old, you should know how to...

Brew your own coffee.

One of these days you won’t be able to afford Starbucks (not that you can now either, but whatever). Plus, coffee is one of those things that tastes exponentially better when you make it yourself.

Sign your name with a bomb-ass signature.

That way at least you’ll receive a tiny bit of satisfaction when you sign receipts for all those overpriced and probably unnecessary purchases.

Tell someone how you really feel.

Like in a straight up, no bullshit kind of way. We’re not in high school anymore.

SEE ALSO:5 Reasons Why You Should Date The Girl Who Goes To The Bar Alone

Write a professional letter or business email.

Because no one important is going to take you seriously if you start with, "I just really feel like..."

Give a genuine apology.

Texting doesn’t count.

Stand up for what you believe in.

Life’s too short to dilute your opinions, however crazy they may be.

Let go of old grudges.

This one’s for you, ex-BFF.

Write a killer resume.

Complete with coordinating fonts and your many accomplishments.

Tell that guy off.

You know, the one who only texts you at 2 a.m. or your ex-boyfriend who cheated on you but keeps coming around. Tell him off. You don’t need anyone in your life who doesn’t act like he wants to be there.

Kiss someone properly.

The kind of kiss that wouldn’t be awkward if your grandma saw.

Kiss someone improperly.

The kind of kiss that would.

Own up to your mistakes.

Unfortunately, you're officially too old to blame everything on your younger sibling.

Dress business casual.

Nothing says badass like a blazer and black pumps.

Let go of the small things.

Because sometimes it's just too exhausting to start World War III over the shirt your sister borrowed without asking.

Handle your alcohol.

Let’s be real here. By the time you reach the big 2-0, being sloppy drunk and throwing up in Ubers become less humorous and more annoying. Know your limits.

Put on liquid eyeliner.

Or at least have a friend who's good at it and down to be your personal makeup artist. The world will never know.

Defend your choice of major.

Even if it’s not set in stone, you should be able to relay your passion for whatever it is you’re studying to someone who asks. If you can't, change your major.

Same goes for your favorite band or music artist.

And “he’s hot” doesn’t count, home girl.

SEE ALSO:Girls, We Gotta Stop Letting Guys Define Our Happiness

Take a decent photo.

Filtered selfies of half your face and Snapchat stories of your best friend taking a tequila shot are really great and all, except they’re not. Take pictures of people when they're laughing so hard they're crying and the sunrise on the way to your 8 a.m. class.

Walk in heels.

Not knowing how was only cute at high school dances.

Make at least one food item that you’re damn good at.

It doesn’t have to be worthy of a "Top Chef" appearance, but a mean mac n' cheese or killer omelet will be your saving grace when you’re hungry, broke, or busy (a.k.a., always).

Read a book all the way through and enjoy it.

If you didn't know how to do this before, you're missing out.

Fend off men.

Roll your eyes at the boys who try to hit on you while in class, ignore the ones who yell catcalls when they pass you on the street, and give the middle finger to guys who honk as they drive by when you’re on a run. You’ll get a lot of practice with this one.

Look good.

Wear clothes that your body type can rock. Know the way you like to do your hair, but don't be afraid to change it up every once and awhile. Do your makeup the way you like it. Wear colors that bring out your eyes.

Last but not least -- get your crap together.

Just kidding. No one has their life together by the age of 20, and you’re not supposed to.