How to look great in a photograph...

As the hysterical rapture subsides after the publication of Diana's "extraordinary", "sensational" and "very sexy" photographs on the cover of July's Vanity Fair, one question niggles. Given that she has access to the best lighting, make-up and photography that money can buy, why doesn't she look this good more often?

Photographed by Snowdon she looked cold and formal, but through the flattering lens of Mario Testino in Vanity Fair, she looks anything but. Di may be the most photographed woman in the world but, rest assured, when it comes to looking her very best she's down here with the rest of us. For her, like everyone else, truly flattering photographs are like gold dust. Look no further than self-conscious "meeja" circles, where the image of so many authors and celebs rests eternally on that one mugshot above their name, sultry, black and white and invariably ten years out of date. (See all Birchill's bylines. Ditto Amis.) Who can blame them though, when you consider the horrors contained in most of our photo albums?

So, why is a pleasing photo such a rare occurrence? According to the image experts, it doesn't have to be, with the help of some simple techniques. They say lighting, make-up, poise, and, yawn, "inner confidence" are as important, if not more so, than what you actually look like. Robin Derrick, art director for Vogue, gets nearer to demystifying the whole process. "To look good you need an awful lot: a great looking subject, great clothes, great hair, great lighting. And then you've got a chance." The rest will always be hit and miss - as even Diana has discovered. With this in mind, the following guidelines can at least improve the odds...

1 Attitude

First, and most important, relax and "be yourself." It's absolutely vital, say the experts. For proof, see this month's Vanity Fair pictures - if Di were any more relaxed she'd be comatose. Make-up artist Sally Kvalheim says, "The important thing is to be comfortable with yourself, not tense." Damien Demoulder, technical writer for Photo Technique magazine, has a novel approach. He always asks his models to say "Dog shit." "It makes people laugh and then you can take the picture while they're smiling."

2 Bonding

Building up a rapport with the man (or woman) behind the camera is the key to looking relaxed. So why should it be that loved ones in possession of an instamatic have such a tense effect on their subjects? Because they're probably not skilled in putting their subject at ease. Fashion photographer Peter Warren says, "It's making the model feel good. My way is to say something encouraging like, 'You're looking beautiful.' It sounds like a cliche but it works." Robin Derrick says, "In the Vanity Fair shots Diana is laughing and mucking about because Testino is a charming, funny man."

3 Lighting

Avoid bright sunlight and stick to something more subtle and diffuse. "Use nice side-lighting. Harsh sun makes you squint and can give massive nose shadows," warns Demoulder. He also recommends shooting outdoors: "Stand in the shade or wait for an overcast day." Newspaper photographer Jason Buckner advises, "Use a lot of light on the face to get rid of shadows and shoot down if they've got a double chin. If you're inside stand by a north-facing window with net curtains so the light is diffused." If all else fails, Buckner suggests one fool-proof addition. "Use a diffuser for a soft, hazy look - a pair of tights over the lens can work."

4 Strike a pose

If you want to look thinner Demoulder suggests sitting slightly sideways rather than straight on. "It can give the picture more depth and your body less width." Also, be aware of your hands - they often get in the way. Demoulder says, "Don't put them behind your back - you'll look like you're in a football team. Don't lean on them either - they can squash your cheeks. They're best kept in the lap." Keep your back straight and chin up and be aware of posture.

5 Make-up

We all know that the au naturel visage doesn't exist in photography - it's the result of a make-up artist who's deployed a ton of base and powder but skillfully disguised the fact. Experts are divided on whether or not to make-up for the camera. "Wear more foundation than normal - make it slightly heavier because photographic lights tend to show up all the blemishes," recommends Demoulder. Kvalheim disagrees. "Unless you're used to it, don't overly make-up. You'll automatically feel uptight and you won't be comfortable with yourself." If you want to disguise the plumper face, there's always the Liz Taylor technique; she famously wore a turban to pull back the surplus, giving a leaner, taut look.

6 Know your strong points

If you're vain enough to have read this far then this last guideline shouldn't seem too self-obsessed. Spend time poring over your photographs and noticing where you're going wrong. After about a year, you can learn how to look in front of the camera. Demoulder agrees. "Look through pictures and decide what you don't like. Then work out how to avoid those things." Learning which expressions are the most photogenic is probably the soundest advice. It makes all the difference to know whether a pout to the camera can give you sexual edge or just a couple of extra chins.

Where did they go wrong?

Be honest. Two 'IoS' guinea-pigs expose their worst, and best, snapshots to professional scrutiny

EMMA

David Sandison, picture editor: "In the first photo, the printing makes her look particularly cold and pale. She's got very pale skin so she should wear a bit of of make-up - I'd also warm the lighting up slightly. The second shot is nicely side-lit. She looks more comfortable not smiling."

Mykel Nicolaou, photographer: "In the first shot, the framing and red- eye reduction could be better. She should be given the chance to pose beforehand - closing the eyes just before the shot relaxes facial muscles. The next pic is obviously better framed and the hands create a nice tension."

IAIN

DS: "In the first one, he's been shot with an amateur flash which doesn't do him any justice. I'd photograph him with a slightly uneven light to give more texture to his face. Also, I think he's got quite interesting eyes, so I'd drop his chin down and make him look up. In the next shot, he's concentrated towards the camera and he's got a really nice smile."

MN: "There's too much shadow behind Iain in the first picture - one of the biggest pitfalls in snapshots. Like Emma, he should be given more of a chance to pose before the shot. The next one has caught a nice moment. The smile is really infectious."