There is a refreshing simplicity to Doug Richard's advice to budding entrepreneurs. The star of the hit BBC series Dragon's Den, Richard eschews management speak in favour of straight-talking good sense.

In Belfast to judge the all-island 2006 Student Enterprise Awards recently, Richard didn't mince his words, but nor did he try to make entrepreneurship sound easy.

"You can teach someone a great deal about the mechanics of starting a new business, but you can't provide them with energy or resilience or endurance or spirit. You've got to have these things yourself," he says. "You've got to appreciate that starting a business takes a huge amount of work. You're going to be under-resourced, under-staffed and certainly under-capitalised, so you have to make up for it by pure effort and imagination."

American-born Richard has made a personal fortune from his forays into entrepreneurship. He has started five companies - the latest just two weeks ago - and sold three. He is best known, however, for his role as a judge on the television series Dragon's Den, giving feedback and advice to entrepreneurs on the pitching process.

"The most important thing to remember is that any business proposition can be boiled down to one sentence. That sentence should describe the benefits you provide to someone else.

"It shouldn't be about a product's features or technology because customers don't care about that and neither do investors. You're normally solving a problem and that's how you should describe it."

So what sentence would Richard use to describe, say, Microsoft? He doesn't hesitate. "Microsoft provides productivity applications to help people use computers more effectively and also the underlying software that makes those applications work."

He grins. "Not a single business, no matter how complicated, can't be boiled down to a single sentence."

Anyone planning to pitch to investors needs to have a clear idea of the kind of questions that they're going to be asked and have answers to hand, says Richard. "The easiest way to figure out those questions is to make a list of every single risk that is in front of you and ask yourself what you can do to reduce that risk.

"Inevitably, you'll find that your list is quite long and your answers are quite thin. But the more you think out your answers, the more credible, the more believable you become as an entrepreneur," he says.

Under-estimating risk is one of the biggest mistakes entrepreneurs make: "There's always risk. That's why most businesses fail."

Another big mistake is over-estimating the size of the market. "You have a product that can be used in lots of different places, but people often forget that you're only going to reach a percentage of that because you're small. There's a big difference between the available market - the total number of people who might use your product - and the accessible market, the total number of people you're going to be able to reach."

For someone so immersed in start-up businesses, Richard started out as an attorney in Los Angeles, a career which lasted just 28 days. "I'm not a good employee and that was made perfectly clear to me. I'd also chosen an occupation that didn't suit me at all. I was bored stiff."

With his brother he started a computer company and five years later, they sold it for a handsome profit. A month later, Richard created another company and again sold on after five years. "Every single business I ever started had a very clear plan, but every single one ended up completely different. The entire shape of a business evolves over time and you've got to be pretty flexible. You can't assume you're right and the world is wrong."

After selling his last company in 2001, Richard moved to England and again began creating businesses. His current projects include a business angel company in Cambridge, a business information firm called Library House and his latest venture, a text over the internet start-up. "Our proposition is that we provide unlimited texting for just €1 a week," he says.

So what's his overall business philosophy? "Business is not complicated, yet it has become complicated in the minds of many people. It sounds like I'm trivialising it, but I'm not. Businesses most often fail because people don't follow basic principles or common sense."

The 2006 Student Enterprise Awards was sponsored by Enterprise Ireland, Ulster Bank and Invest Northern Ireland.