A guide to sunglasses: What shape suits you best, and the styles to avoid like the plague.

This is an extract of fashion journalist Alyson Walsh’s book, Know Your Style: Mix it, Match it, Love it.

When we meet, Marie Wilkinson, design director at Cutler and Gross, is wearing a beautiful pair of 1950s-style brick-red frames. ‘They’re called A Day at the Races,’ she tells me, ‘I was thinking about jockeys and how they want to be distinctive but don’t wear logos, just vivid colours. The colours are very dense, very high pigment, so you can see them from far away.’

Having worked with the eyewear brand for 33 years, and worn glasses since the age of eight (when her mother noticed she was sitting very close to the television), Marie has experimented with a range of different styles: from pink 1960s ‘kitten eye’ to round acetate frames in glittery black. Eulogising over eyewear as a glamorous fashion accessory rather than a mere ‘medical appliance’, she offers advice on what to look for when buying new frames.

Fit, size and shape

First, the basics: ‘Ensure the glasses frame the eyes and the eyes are the focus and sit centrally in the eye rim.’  Then you can start thinking about shape. ‘If you want something to open up your face, choose frames with a wider shape.

'For a small face, I would suggest an oversized, fine-rimmed metal frame for a playful take on proportion, or an immaculately fitting acetate frame. If you go for something bold then make sure it follows a natural line on the face – it could be a fringe, your eyebrows, jawline or cheekbones. There is something to celebrate on everyone’s face. The classic kitten eye is a recurring theme for me; it works with my hairstyle. If it’s the eyebrows, then ensure the frame follows the brow line, and runs just underneath the brow line to emphasise its sweep.’

Complement your look

Glasses are part of your complete look, so consider how they work with your make-up and clothes. ‘Choose a colour that makes the eyes pop and enhances the iris colour. Like make-up, eyewear is a positive way to add colour to your face. If your signature lipstick is non-negotiable, then work with the lipstick. Make sure the frames are an opposite colour or it’s a red that’s in tune.’

It’s important to consider the bigger picture. ‘Glasses should flow. We always have full-length mirrors in our stores so that customers can step back and look at the whole silhouette.’

The je ne sais quoi

As with all things style-related, following your heart or your gut instinct is often the way to go. ‘You should feel something, feel curious and want to try them on. Apparently there’s something like 10 per cent nostalgia – the frames remind you of someone and give you a warm fuzzy feeling – and the rest of it should be new and exciting.’ And when you find the perfect pair of specs, don’t be afraid to make a serious investment: ‘Having bespoke eyewear is a bit like having a suit made to measure: you’re looking for longevity. It’s an investment. Glasses can be re-polished and realigned – you can keep them forever.’

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And what doesn’t go

Wilkinson is not a fan of glasses on chains. ‘I don’t like it and it doesn’t look right at any age. It’s dangerous because your glasses are vulnerable.’ She suggests going for varifocals instead. And, of course, the only thing worse than bad glasses is no glasses at all. ‘Don’t read the menu with a mobile phone light. It’s more chic to have a pair of glasses.’

Great glasses brands to consider: Cutler and Gross, Oliver Peoples, Ray-Ban, Moscot, Warby Parker, Cubitts, Bailey Nelson, Eyevan, Prada.

How to wear glasses with hats

People often think that because they wear glasses, they can’t wear hats. That it feels fussy and hemmed-in and there’s too much going on. But there’s no need to go for the full-on Audrey Hepburn in My Fair Lady approach.

Simply avoid hats where the rim sits on the top of the glasses frame and look for simple styles that allow a bit of space. Show the face in a beret, cloche or turban. For special occasions, doff your cap to the Advanced Style set whose flamboyant outlook often involves the combination of Schiaparelli-inspired shapes and statement specs, or big hats and big glasses. After all, no one thinks twice about wearing a big floppy straw sunhat or a Stetson and sunglasses in summer, do they? As Wilkinson says, ‘Glasses and hats are a yes! A wonderful opportunity for colours and shapes to play together.’

Earrings that you can wear with glasses

Small to medium hoops, studs, cuffs and diamonds – and various combinations of all of the above – go with glasses. Chandeliers? Well, Jenna Lyons does it, usually with her hair tied back. I’m not a glasses-wearer just yet (though long overdue an eye test), but I can see that the tendency is to go for a necklace or strong lips over doorknocker earrings. Keeping it sleek means less clutter around your chops and often statement glasses are enough.

Sunglasses go with everything

No longer for shady show-offs, sunglasses are an essential year-round accessory that shelter the eyes and proffer seclusion. Pick a pair that you like when you put them on. I love super-sized specs but if I wear them my small features are swamped, so I currently move between a cat’s eye style bought on the cheap at Century 21 in New York and fail-safe Ray-Ban Wayfarers.

Personality and mood are other considerations: for every proportion-practising Yoko Ono there’s a statement-making Iris Apfel.

Here are some styles you can try:

The bigger the better! The 1970s was the decade when sunglasses expanded, when women like Natalie Wood, Donna Summer and Jackie O showed us how to go super-sized in style. Feel like having it large? Check out fashion editor Giovanna Battaglia’s take on statement shades for inspiration. For maximum effect, wear hair tied back.

The iconic cateye: This style exudes old-school glamour: from 1950s Grace Kelly in a turban to Solange Knowles in Linda Farrow shades. Black frames offer timeless elegance, while tortoiseshell, embellished or coloured ones add punch to a vivid outfit.

Aviators forever: See Gloria Steinem and Gwyneth Paltrow for tips on and how to wear classic metal-framed shades. And leave mirrored lenses alone.

Keep it kooky: There’s a fantastic photo of Peggy Guggenheim in surrealist butterfly-shaped sunglasses that are both far-out and fabulous. These are the sunglasses to wear when you want to get noticed. See also Rihanna in vintage Chanel pearl sunglasses and Kate Hudson in Cutler and Gross’ red, heart-shaped frames.

Square sunglasses: Sophia Loren wore them in the 1960s, LaDoubleJ’s Viviana Volpicella wears them today. It’s not that Italians do it better; it’s just that wearing sunglasses has always felt like part of their DNA. It’s part of everybody’s now, so square up. Tip: leave hair loose to take the edge off.

Get–a-round: As Beyoncé and Linda Rodin prove, round frames look best with hair pulled back. Add a strong lipstick or big hoop earrings to complete the look.

This is an edited extract from Know Your Style: Mix it, Match it, Love it, by fashion journalist Alyson Walsh. You can purchase the book by Hardie Grant from Booktopia for $19.95.

For more from Alyson, follow her blog That's Not My Age, a grownup guide to great style, here.