The prospect of putting on a bathing suit is enough to fill most women with dread. But to those of you worrying about cellulite or the size of your bottom as you prepare for your holiday, I say: relax.

Nearly two decades as a swimwear designer have taught me that any woman, no matter what her age, and regardless of whether she is a size 8 or an 18, can look great on the beach.

Yes, the stars who wear my designs, from Beyonce to the Duchess of Cambridge and supermodel Cindy Crawford, have enviable physiques.

But I firmly believe that the way you feel about your body, and the mindset with which you approach baring much of it in public, are far more important than the circumference of your thighs or the date on your birth certificate.

And with some clever styling tricks and simple preparation, you, too, can look paparazzi-ready.

So, here are my top tips to classy costume wearing — my swimsuit psychology for a happy summer...

SHRINK TO FIT

First, a warning about my pet peeve and the most common mistake women make when swimsuit shopping.

Don’t buy a size up because you think more fabric means better camouflage for your wobbly bits.

In fact, the opposite is the case. Excess material simply adds bulk and a high risk of a saggy bottom.

Buy your exact size — or even a size smaller — to create the illusion of looking smaller than you are, and make sure that the costume fits tight against your body.

Be brave: showing two or three inches of buttock cheek is important — it will enhance the shape of your derriere, which will look less appealing if it’s entirely covered in fabric.

Although a high-rise cut is fashionable at the moment, a costume that finishes lower on the hip is generally more flattering for bigger bottoms.

LIGHTING STRIKES

The glaring ceiling spotlights in most shop changing rooms are unflattering enough to make even supermodels look like they have cellulite.

So it’s little wonder that we often leave dismayed and empty-handed.

That’s why, in our store, we mimic the natural effects of daylight by positioning lights at the sides of the cubicles and behind the mirrors.

Alternatively, order online and try in the comfort of your own home, where you’ll get a much better idea of how well a costume fits.

On the beach, cloud cover is more forgiving, as sunshine highlights imperfections — worth remembering when you’re deciding just how much flesh to reveal and how bright you want to go with the colour of the costume.

AGE IS JUST A NUMBER

No woman should relinquish her bikini just because she hits a milestone birthday.

Look at model and swimsuit cover girl Christie Brinkley — she’s 63 and she still looks sensational in hers.

If you feel confident, you’ll look great, and high-waisted bikini bottoms can work wonders at disguising wrinkly stomach skin.

That said, swimsuits are so fashionable right now that even twentysomethings are ditching their two-pieces.

No matter what your age or how pert your posterior, however, please don’t be tempted by a thong: they’re just plain vulgar.

OVER THE RAINBOW 

Lots of British women tend to think they’re too pale to buy colourful swimsuits.

But this is a myth — sky blue, for example, can look striking against most fair complexions. My only word of caution would be that big, bold patterns can make you look bigger.

Block colours or intricate patterns are, broadly speaking, more flattering for fuller figures.

A black one-piece is timeless, slimming and will make any woman look elegant, while I have a weakness for white, which can’t be beaten for showing off a tan.

I’d stick with neutral colours, such as animal prints, at the start of the holiday when your skin is still pale. Build up to whites and brights — a personal favourite is yellow — once you’ve built up a tan.

Make sure that your swimsuit is thick enough so as not to become embarrassingly see-through when wet — all my fabric is double-lined for this reason.

And always handwash (whites should go only with other whites) with a mild detergent straight after wearing to remove any sun cream marks and make sure it stays pristine, and dry out of direct sunlight or the colour will fade.

SEAFRONT STYLE

How you wear a swimsuit is so important. When sunbathing, keep one leg straight and the other bent — your legs will instantly seem slimmer.

A sarong will disguise a bloated stomach or larger legs en route to the bar, but don’t clonk around in heels — even wedges — to make your legs look longer.

Sinking into the sand isn’t a good look. A flat, metallic sandal is far more flattering.

Ruching is a clever way to disguise a wobbly tummy and create an hourglass shape, and swimsuits that claim to control your body shape can certainly make you feel more confident, even though they are unlikely to dramatically change your shape. A clever cut doesn’t need underwiring — some of my designs are created without it for a closer fit, for better movement.

A halter-neck style actually allows more support, because it can be better adjusted, and is the best way of creating cleavage.

LAST-MINUTE TRICKS

A deep tissue massage improves the lymphatic drainage system, helping to reduce cellulite and water retention, while avoiding refined carbohydrates, such as white bread and pasta, in the days before a holiday can quickly banish bloating.

Drinking two litres of water daily also helps skin glow.

Exercise-wise, I think the best activity to maintain a slim, firm body for the beach is running.

I haven’t gained a pound in the 20 years that I’ve been jogging — plus, you can take your trainers just about anywhere.

SKIN DEEP

While everyone looks better bronzed, there’s no need to spend a fortune on professional tanning.

If I don’t have time for a spray tan, I do it myself with a mitt the night before I fly.

Too late for that? Blast a showerhead of freezing cold water over your legs for five minutes before you hit the beach.

I acquired this tip from a ballerina I once lived with who did it every day. While it’s not the most pleasant sensation, it will give your circulation a boost and temporarily tighten your skin.

PICTURE PERFECT

The camera can lie — actress Eva Longoria recently posted two pictures of herself wearing one of my swimsuits on Instagram.

The first was taken from eye level and the second was a selfie taken from above her head.

The latter picture instantly made her look taller and slimmer, because taking photographs from above is more flattering.

If you’re over 20, avoid having your picture taken in direct sunlight — the shade is kinder to skin tone, and a snap taken at sunset is the most forgiving of all.

COSTUME CONFIDENCE

Material with a good stretch helps the swimsuit fit and last — my costumes are typically 14 per cent elastane and double-lined so that they look more luxurious (and don’t become see-through).

Most women who wear my designs aren’t as slim as the average A-lister, and I also work with lots of plus-size models who look just as hot, thanks to some clever ruching around the torso.

This can emphasise hourglass figures and disguise imperfections, while seam-free designs that give the perfect fit.

Body confidence is the key — as long as you believe you look good, and buy a costume that suits your frame, you, too, can be a beach babe.