Why buy throwaway fashion when a needle and thread can transform what you already own?

Like forcing prisoners to make their overalls, my first sewing project was to make my own school-uniform skirt. It was a disaster. It looked like a navy potato-sack, and where I hadn't been able to fit the zip, I'd just tagged on extra bits of material. Frankly, it was a Franken-skirt. My mum bought me one from Topshop, which had multiple pockets sewn on by some poor woman in India instead. I carried on making my own creations, though – a batik skirt from a sheet; a green and black lace Goth dress – all appallingly sewn, until I did what everyone else does and started buying stuff from the high street.

Not only have we, as a nation, largely forgotten how to sew our own clothes, we've also lost the art of "make do and mend". One woman I know buys her children's shirts from the supermarket. When the buttons come off, she replaces the shirt as she says it's cheaper and easier than sewing them back on. In the past decade, clothing sales have risen by 60 per cent – that's two million tonnes of clothing a year we're consuming, more than half of which ends up in the bin.

Lilli Rose Wicks hopes to change our habits. In 2007, she won the Visionary Knitwear award at Graduate Fashion Week, and was inundated with offers to design for the high street. She turned them down as she felt the stores weren't willing or able to change their environmental practices. Wicks' work is made from organic or recycled materials. Her passion has always been to make or refashion her clothes rather than buy them new. "Before I buy anything, I work out whether I can make it myself," she says.

Wicks now runs workshops, in collaboration with the Soil Association, on customising clothes, and that is why I arrive at Wicks' cottage in Somerset with an armful of my own clothes, which, instead of joining the 300,000 tonnes of garments that end up in recycling bins, are going to be refashioned. I'm nervous because, having first-hand experience of my sewing, I'm not sure I want to mess about with my clothes. "Sewing is something you can learn. Everyone starts somewhere," Wicks assures me. Having spilt oil on a skirt I like, I'm hoping Wicks can help me hide the stain so I can keep wearing it.

I'm reassured when Wicks shows me some of the items she has refashioned. There's a skirt made from khaki trousers, all edgy pleats and funky red stitching, and another with tiny mirrors embedded in Rajasthani-like embroidery. It turns out that the "mirrors" are cut out of beer cans, and the thread is from a charity shop. "Customising your own clothes is creative and satisfying, as you feel you've produced something that is completely yours. Consuming is dull," says Wicks.

We decide to add a nifty pocket and edge my grey skirt in a gorgeous two-tone shot silk from Wicks' box of material tricks, and embroider over the stain. Wicks allows me just one tiny practice before fitting an embroidery hoop on my skirt and handing me some purple thread. "Making and altering your own clothes is much simpler than people make out," she says.

Wicks has been sewing clothes since she was a child, starting with outfits for her dolls. Her father is an upholsterer and her mother makes clothes and soft furnishings. "It's in my blood," she says. As for her ethical views: "Recycling was passed on to me by my parents. We've always done it, it's part of my life, and it has become intrinsic to my work. But although I think it's good to recycle, it doesn't solve the problem of where the materials we use come from. We should look towards organic fabric and yarn."

Her dresses from her graduate show are hanging over the Aga. They're hand-knitted from charity-shop yarn, and look old because she dip-dyed them in tea. They're delicate pieces, and to appreciate their inherent movement, you need to see them being worn. "Everyone seemed to spend hundreds of pounds on their materials," says Wicks, "but I spent about 50p."

The embroidery takes ages and the back of my skirt is a tangle of purple thread. But it is strangely soothing. "People say that they don't have time to sew, but they could watch less TV," says Wicks, "or sew in front of the TV." She shows me a beautiful quilt she has been hand-sewing for four years. I'm not sure I have either the ability to multiskill, or the perspicacity.

Wicks helps me with the fabric to edge my skirt, ironing it before we start sewing. "There's a lot of measuring and maths involved – you have to be quite precise and that can put people off. And there's a lot of ironing, more than you want or need," she adds.

The machine – a 40-year-old monster – is similar to my mum's. "People start off by buying an amazing piece of equipment," says Wicks, "thinking they'll achieve some amazing item of clothing – but you can do amazing things with a needle and thread."

For anything more tricky, I might be tempted to call in the services of Junky Styling in London, which offers Wardrobe Surgery. When I visit, they have customised a pinstripe jacket so that it is now fitted and edged in denim. Founded by Annika Sanders and Kerry Seager, Junky Styling sells quirky, radical designs created from charity-shop finds, and even sell in Topshop. There's a basque made out of a man's suit, shirt cuffs that have been turned into a waistcoat, a bolero from a pair of trousers, and a dress that was once a shirt. "We started out as skint teenagers who had a passion for retro clothes and wanted to look different, so we used to raid charity shops and customise our own clothes," says Sanders.

Now the pair have an outlet in fashionable Shoreditch. "We're not about being greener than thou," she explains, "but we do think people should be responsible for the environment, reuse resources, and be more considerate about their consumption," she says. The Junky Styling skirts, with their wavy, tulip-shaped hems, are more extreme than anything I might be able to make or wear, but it's inspiring to think what you could do with an old suit and a bit of imagination.

How to customise your clothes

* Change the buttons on your garments, either by using buttons from other garments that you no longer wear, or picking them up from charity shops.

* Sew and tie thread to make a knot in a tired top; building up a number of knots creates a simple but effective pattern.

* Simple, hand-stitched embroidery can transform a garment. More rather than less is better.

* Sew beads or sequins on.

* Buy clothes from charity shops and practise on them.

* Cut up old T-shirts – the material doesn't fray.

* If you can't sew in a zip, make ties out of stretchy leggings, shirt sleeves or ribbons.

* Take elements from clothes and turn them into something else: several pockets can be linked together to make a belt; shirt sleeves could become a scarf; the lapel from a man's jacket can be refashioned to make a halter-neck waistcoat.

* Pick up sewing machines on freecycle.org or eBay, buy thread in charity shops, and try car-boot sales for any other equipment.

Lilli Rose Wicks workshops: www. soilassociation.org; lilliredrose@yahoo.co.uk

Junky Styling: 020-7247 1883; www.junkystyling.co.uk; shop@junkystyling.co.uk