By Danielle Rossingh BBC News Online business reporter

The first Coffee Republic opened with a �70,000 bank loan

As part of a new series on small business, BBC News Online looks at how would-be entrepreneurs can get their ideas off the drawing board.

Imagine this.

You have got a brilliant idea to set up a business.

You're certain that your company, once off the ground, will make you a lot of money.

The only problem is that you have no funding.

What you need to do is write a cracking business plan to persuade potential investors to turn your idea into reality.

Get real

A sobering thought - half of all business start-ups fail in the first four years of their existence.

"A business plan is like a novel," says John Weston, director of director development at the Institute of Directors (IoD).

SMALL BUSINESS, BIG IDEAS The UK's first ever National Small Business Week has highlighted the contribution made by smaller companies to the economy. In a new series, BBC News Online profiles entrepreneurs and examines some of the challenges facing small business.

"It is a total work of fiction until you give it a good reality check. Most people can come up with a good idea and write a business plan.

"But the hard part is the implementation stage. That is where a lot of potential businesses fail to make it."

Mr Weston advises that before approaching a bank, you should give your plan a good reality check.

Is the plan viable and is it based on the right assumptions?

"For example, expecting pay-back after 12 months is probably too optimistic. A more realistic time frame would be three to five years."

Bubble fall-out

In the current business climate, a good plan has become a pre-requisite.

"A good business plan is important, probably more important that it was a couple of years ago because investors have become very cautious," says Nigel Piercy, professor of strategic marketing at Cranfield School of Management.

A good business plan will tell you what you want to achieve and how you are going to achieve it Nigel Piercy Cranfield School of Management

The internet bubble, the global economic slowdown and turmoil on the stock market have made investors wary of putting money into new business ventures.

Online fashion retailer Boo.com managed to raise millions of pounds from investors during the internet boom.

"Investors were practically throwing money at them, without realising they actually didn't have a competitive advantage and that their costs were far too high," Mr Piercy says.

Their lack of a good business plan was forgiven because they claimed that matters were moving so fast in the online world that a plan would soon be outdated.

But in spite of all the cash, Boo.com eventually succumbed to the pressures of the real economy and collapsed.

Health check

In the aftermath of the "dot.bomb" era, it may have become even more difficult to access funding.

"Investors have grown up," says Mr Piercy. "They now realise old-fashioned business principles like profitability and solid cash-flow do account for something."

Business plans serve two purposes.

First, banks and other financial institutions normally request them when start-ups seek funding.

And once a company is launched, most investors will want to see an annual business plan showing them where the business is standing now, what the goals are and how to achieve them.

Winning idea

Sahar and Bobby Hashemi once had a dream.

They were both working in the City, when Sahar mentioned to her brother Bobby how much she missed the skinny cappuccinos and fat-free muffins she had developed a craving for while on a trip to New York.

They first discussed the idea of setting up a business over a Thai meal in November 1994.

Their first Coffee Republic bar was opened with a �70,000 bank loan exactly a year later.

And the rest, as they say, is history.

The first bar became a success and they managed to secure further funds from an angel investor to expand their business.

Coffee Republic went public on the London Stock Exchange in 1997 with six coffee bars.

There are currently more than 100 bars.

Good discipline

"Our business plan was crucial for us," says Sahar Hashemi.

"Having a brilliant idea is one thing, but you need a good plan to get to the next level.

"A business plan is like an itinerary when you go on a trip, you cannot start a business without one."

The assumptions in the first business plans for Coffee Republic were always realistic.

"My brother said that we had to live up to our business plans, and we always did. In a sense, putting a plan down on paper is forcing you to be very critical about yourself and your business."

Plan's purpose

"Once you are in business, what matters most is not the actual plan itself, but good planning," Mr Piercy says.

"Make sure you involve a variety of stakeholders, such a suppliers, customers and marketing in your planning.

"A good business plan will tell you what you want to achieve and how you are going to achieve it.

"It will also tell you where your market is and how you are going to create value for your customers and shareholders.

It is crucial to include numbers, such as profit margins on your products and cash flow.

"Profit is a matter of accounting convention, only cash is real," adds Mr Piercy.

"Or to quote Jerry Maguire: 'Show me the money!' That is the only language investors really understand."