Buying sunglasses can be a thrill or a trial. The most important part of buying sunglasses is knowing your face shape (you can find yours out by reading my instructions here). Different frames suit different faces. Here’s what works:

Oval face: Just like with choosing a haircut, an oval face is the (ahem) “ideal”, meaning that most shapes will suit you. Go nuts, ye of the blessed face shape!

Round face: You’ll want frames that make your face look longer & slimmer. Frames that are equal to or a little wider than the broadest part of your face will help achieve this. You can add some definition by going for frames that are quite angular or rectangular in shape.

Diamond face: As your face is quite angular naturally, oval-shaped sunglasses will soften you. You can also try gently curved square frames. You will look best if the frames aren’t any wider than your cheekbones.

Square face: You can reduce the squareness of your face by wearing frames that are soft & curvy while having a strong shape. Cat’s-eye frames are ideal, as are ovals & round shapes.

Oblong face: Frames shouldn’t extend past the widest area of your face. You should go for round & square shapes as this will widen & shorten your face.

Triangle/heart shape: The aim is to make the jaw look narrower, & the best way to do this is by accenting the eye area. Cat’s-eye styles are good as well as metal frames with rimless bottoms.

Black frames seem to be the most popular choice when it comes to eye-wear, but be careful that it doesn’t look too harsh on your face. Or that you don’t look like Stevie Wonder. (It is easier than you would imagine.)

Don’t be afraid of sunglasses with coloured frames, especially if they’re in a colour you wear often. I once owned a pair of turquoise sunglasses which I absolutely cherished… but one day they broke. That’s not the point. Experiment! Try on some colourful sunglasses, they tend to be far more interesting than the others.

If black looks too harsh & colour isn’t your thing (oh shush, go read my article), try brown or tortoiseshell. Even if you don’t wear brown EVER, they’re a good choice because they’re neutral. Trust me, they will work with any ensemble.

My best sunglasses tip is this: go to a department store with a huge range. Take a camera. Photograph yourself in various styles (or have your friend do it if you’re too embarrassed to pose alone). Most sales assistants with a clue won’t mind. Just say you want to have a think about it. Before you leave, be sure to get the model number of the ones you like. Then search Ebay for the same ones. I bought my Dolce & Gabbana sunglasses (which I LOVE) for 1/3 of the price my local department store wanted. (When buying off Ebay, always check the seller’s feedback to make sure they’re not selling fakes.)

For the fashionable, the word on the street is that big round sunglasses are heading out of style. Of course, this doesn’t mean you have to stop wearing them, but it DOES mean it’s going to be harder to buy them. If you’re a fan, as I am, I suggest you snap ’em up soon.

A lot of people think you should have two pairs of sunglasses — one for casual attire & one pair that is more glamourous. Some of you will think this is excessive, but some of you would feel under-prepared with only two pairs. I have more pairs of sunglasses than I care to count, but only three that I wear on a regular basis. Oh, okay, four. Getting contact lenses a couple of years ago means I can actually wear sunglasses, & after years of OPPRESSION I embrace the opportunity!

Finally, the key point is that your sunglasses should make you feel like a superstar. If you have to spend a little more than you wanted to in order to achieve this, don’t worry about it. Sunglasses are important. You should be able to slide them on after a tawdry one-night stand when all your make-up has smeared off & walk home feeling hot & powerful. The best sunglasses transform you — really. I remember once Ashley Olsen was asked why her & Mary-Kate wore big sunglasses all the time. She replied that sometimes, when they went out, they just didn’t feel like wearing make-up. Your sunglasses should enable you to go from an uncoiffed mess to a sleek master of your own destiny. Don’t settle for less!

P.S. I the sunglasses Karen Walker is doing.