In the exquisitely crammed space of Lachlan Goudie's North London studio I'm sitting on an old wooden stool and gazing over at a pretty still life of antique glass decanters, damson wine glass, lemon, napkin and knife, all balanced on a pewter platter and lit strongly on one side by an anglepoise lamp.

I see the sparkle in the glass, the depth in the liquids, the lustre in the pewter, the plump roundness in the lemon. This, I think, has all the classic elements of a priceless Old Master and I begin to imagine a stunning end result of thick paint, lustrous colours, dark shadows and convincing reflections. Being a mere amateur, however, I've been given 20 minutes to sketch the lot.

I panic.

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Leaning over a blank A10 sheet of cartridge paper which has been clipped over a flat board on the kind of over-the-bed tray you find in hospitals, I pluck up my courage, pick up my pencil - and find that I haven't a clue where to begin. I'm crushed. So much for having got a respectable Higher Art grade at school.

Luckily, the celebrated Glasgow-born artist is hovering at my shoulder. "Try to plot the most extreme points, and don't worry about filling in the lines just yet," he prompts gently. So I put a mark at the top and bottom of the two decanters, at the extreme edges of the tray, and round the wine glass as I see them. "That's very good," says my tutor. I purr.

Then I try the outlines of the objects. This is difficult: I find I'm very out of practice and end up sketching lines timidly rather than boldly taking control of them. Before long I'm over-obsessing. Angles get skewed, perspectives shot. The objects are out synch with each other. Goudie advises me to stop and look again at the whole picture. I'm to imagine the circles: of the glass stoppers, the decorative necks of the decanters, the rim of the wine glass, the base of the objects, the liquids inside them. He shows me how these should be narrow to reflect height, or opened out to convey depth. My page is soon plotted with horizontal ovals and elipses circling vertical cones. Immediately, my objects are erect, balanced, together.

Now I can start on the vertical lines. Goudie urges me not to angst too much but just to get on with it. As a left-handed person with a recently damaged index finger, my hand feels weak and my posture wrong. But these are just excuses. I have to admit the truth: after years of taking any innate artistic talent for granted, I've allowed myself to become a stranger to this drawing malarky. I'm disappointed and embarrassed.

Since I've dabbled in portraiture and figurative sculpture in the past, and still harbour a long-held aspiration to return to these at some point, I'd asked Goudie if I could attempt do his portrait instead of a still life. But he'd been adamant: "Don't start out with portraiture. It's much more useful to start with still life where you learn about volume, perspective and tone," he'd counselled.

"After a while that can be translated to other things. Everything you've learned about drawing, say, a lemon you can translate to painting, say, auntie Mary. But it's like learning piano: you go very gradually, develop incrementally, and start by learning chords and scales."

It's in my interests to listen. After all, Goudie, son of the late Glasgow artist Alexander (Sandy) Goudie, is not only a successful artist in his own right with a string of exhibitions behind and ahead of him (he shows in London, Glasgow and New York; A Place in the Sun opens at the Roger Billcliffe Gallery, Glasgow on February 28, and New Paintings opens at the Mall Galleries, London, next month); he's also a judge on the BBC's upcoming Big Painting Challenge, a new six-part series where 10 would-be creatives vie for the title of Britain's best amateur artist. Although there are no Scots contestants or locations in the series, it hopes to tap into the many people who perhaps studied art at school, or even excelled in early childhood, and want to have another go, be it in landscape, portraiture or still life. After all, drawing without embarrassment is one of the earliest things we do as children.

When he was growing up in "an unbelievably magical house" in Glasgow's west end, Goudie attended Kelvinside Academy and was awarded the RSP prize for painting at the Royal Glasgow Institute of Fine Arts in 1999 and the NS MacFarlane prize at the Royal Scottish Academy in 2001 before gaining a degree in Fine Art and Painting from Camberwell College of Arts in 2004 - the same year his father died.

He says it was his father, whom he physically resembles and whose temperament he says he shares, who gave him his classical grounding in art. "He always encouraged me to go out and draw," he says of Sandy. "He taught me to always look up and see the beautiful details of the buildings around us. Naval design and architecture remain fascinating for me.

"He'd give me huge sheets of paper when I was 8 or 9 and bring out his books on Velazquez. He knew I was into 17th century art. He made it fun. I'd come up with frankly chronic representations of Picasso, but he'd say, 'don't be intimidated by that. Love to paint'.

"My dad was an extraordinary enthusiast, passionate and opinionated. In the summer he'd sit out on the steps of our extraordinary big house in Cleveden Road and speak to people. He'd say, 'Isn't it just f***ing great to be alive?' He lived for the moment, but he was also a very tough boy who could be very difficult. I'm the beneficiary of his enthusiasm. He rooted me in the classical techniques, and I'm very grateful for that.

"I am my father's son, and I do paint in a way that could recognise my connection with him."

On the other hand, he feels there is a difference between his art and his father's. Sandy trained and taught at Glasgow School of Art in the 1950s and 1960s before becoming a full-time painter, in an era when there was a great tradition of Scottish painting based on skill and craft; but the idea of art changed and it became more about representing what you thought about the world than showing what you saw. "Post-modern art was a more cerebral approach and when it came to the fore artists of my dad's generation found themselves in an alien world. That entrenched him in a sense of what represented him."

Lachlan says he feels the need to explore different ways of using paints, pencils and inks, and to put himself in different environments such as the Rocky Mountains, where time spent painting in the open air helped give his painting a looser expression than his father's. "I like to really let go, to fling paint around," he says. "In this, Joan Eardley is my lode star. She helped me decide my future. It's more expressive than just representing what's in front of me."

We meet on the very day that The Herald reported comments by the Paisley-born artist John Byrne that the Glasgow School of Art - which he attended between 1958 and 1963, and whose degree show nudes were purchased by Sandy Gaudie only to be lost in the mists of time - was a "fun factory" and that there was a lack of drawing ability at the school. He made the point to emphasise that "real artistry" has become overshadowed by the attention grabbed by contemporary art awards such as the Turner Prize (where the GSA has excelled). It is all about promotion, he said, and some of it is empty and vacuous and gives students delusions of grandeur.

Does Goudie, 39, agree with the view that teaching the fundamentals of art - life drawing - is being overlooked in favour of conceptual art?

"A lot of art schools in the UK are engaging art in a bit of a charade," he says. "More and more people are being churned out of art school; now it's all about style and corporate sponsorships. This was never the case before the 1960s. Lots of people are going into art school and accruing large debts they think they can pay off later. But from my time at Camberwell, there's only one other student who remains an artist. The rest are in advertising, web design, a little failed by the system. It's what happens when art is made for curators. It has engendered an attitude that if it's not challenging it's not relevant and a sort of art hierarchy has evolved."

He reckons there's nothing more snobby than the art world. "We've got to the point where the only response to a vase of flowers is pity. That's ridiculous. It suppresses the voice of many people who would quite like to do a bit of painting.

"The reason I got involved in this programme is that it's addressed to the hoi polloi or wider public, not to the cognoscenti of the art world. Amateur art is an area that's been dismissed for too long. It's like opening a door to great ideas, great colours and great nourishment for people. Art slows you down and helps you appreciate your surroundings. I decided to give it a shot to encourage people to see it's worth giving it a shot again.

"No doubt the culture vultures out there will knock this show, but who the hell are they to tell people that what they do isn't relevant? I don't like that sense of exclusivity."

And so back to my still life sketch. I feel frustrated by my lack of progress, but he says it's good: "In just 20 minutes you've convinced me that these objects inhabit this space."

To create a little depth, he helps me with shading - putting the lead nib of my pencil flat against the paper and "being bold" with filling in the white. This is most challenging when it comes to giving my lemon a bit of shape. Taking my rubber, he shows me how to erase a sharp white outline around its edge; viewed against the dark background it begins to look better. I smudge a bit of the shadow with my finger, and he's pleased. Creating a convincing lip and indent around the edge of the platter is also difficult. I sense he's trying to keep his cool as I hesitate with my criss-cross shading down one external side of a decanter and again down the back of its inside in an attempt to create the illusion of transparency. But he comments: "I think you have a really nice sense of objects and how they related to one another in space."

I suspect he might be being kind. Surely if you don't have the skill, you just don't have it? "You can learn if you have patience and you're willing to practise, but there's no doubt that if you have absolutely no sense of spatial awareness you're going to find it difficult," he concedes. "However, there's no doubt in my mind that with a little bit of tuition people can gain satisfaction in art, and a real distance from all the crap that life is full of.

"Remember, painting is not just about structure and technique. It's about emotion, energy, unexpected ideas and points of view. Painting is magic. From a blank piece of paper you can conjure up new worlds.

Surveying my effort in 2B, he adds: "The one guarantee with creating paintings is that there's always plenty of rubbing out to be done. Don't be disheartened. The best artistic advice I was given was never be afraid of taking a risk. So I recommend you go and make some mistakes."

As if I haven't made enough already. Thank goodness we didn't have time to apply the paint.

The Big Painting Challenge starts on BBC One at 6pm on Sunday February 22, 2015.