Dozens of books have been written about how Warren Buffett works his financial magic, although none by the Sage of Omaha himself, which is why it was fascinating to watch him being interviewed by Evan Davies on BBC2 last week.

After seeing him speak, it is easy to understand why tens of thousands of people flock every year to hear this avuncular and down-to-earth investment guru dispense some of his wisdom.

His humility was refreshing. "Some people are better at certain things than others. Some people can sing a lot better than I can," he told the BBC's Davis. If bonus rich investment bankers ever hope to win back public trust adopting Mr Buffett's modesty would do them no harm.

Equally intriguing was the insight it gave into the way he makes money. And what a lot of money he's made; the 79-year-old has an estimated net worth of $37 billion (£22 billion).

He does this by breaking one of the supposedly cardinal rules of investing. Investors are constantly told that they need to diversify; that drip feeding money into the stock market each month is a better bet than throwing your lot in all in one go.

That's not Warren Buffett's style. He believes in backing his convinctions - taking huge long-term bets in just a handful of companies. He was at it again yesterday, ploughing $34 billion into America's second largest railroad operator, Burlington Northern Santa Fe - his biggest deal in his 46 years at the helm of Berkshire Hathaway. "It's an all-in wager on the economic future of the US", he said. "I love these bets."

His high-stake gambles don't always pay off, but when they do the results are spectacular. But is it an approach that a private investor should follow?

The benefit of diversifying has certainly been brought into question during the recent downturn. Investors were always told that putting their money into different asset classes made sense because if one type of asset - says shares - was falling, another - property, bonds, cash - would almost certainly be rising.

Although that has been the case in the past, this time round almost all asset classes fell in unison. No matter how hard you tried, you still lost money.

The market bounce since March also argues against the diversified approach. Anyone who took a big bet on equities - particularly emerging markets - will now be laughing. Drip feeding into the market would still have paid off, but a lump sum investment close to the market bottom would have been even more profitable.

That said, the fact remains that any investor who wants a quiet life - and I suspect most do - would be wrong to adopt Buffett's all-in approach to investing. Most of us don't have the brains or resources to spot opportunties like the Sage of Omaha.

Nor can most of us risk our lot in the way that Mr Buffett does. When your company is worth around $150 billion losing a few billion may be easy to swallow. And let us be clear, Warren does get things wrong - Berkshire Hathaway lost $1.5 billion in the first quarter of this year.

Also, although diversification didn't pay off during the last downturn that doesn't mean that it won't work in the next. With hindsight it was apparent that bubbles had appeared in a number of asset classes - housing, commercial property and shares in particular - before the markets popped. That may not be repeated next time round.

However, it is still possible to draw inspiration from Mr Buffett's investment approach. First, he has the courage to back his convinctions. I suspect quite a lot of private investors felt that the market bottom had been reached in March but didn't have the courage to go with that hunch. Redeploying some existing capital or investing spare cash into shares at that time would have paid off.

Perhaps we should all have more courage to back investments we believe in. A core portfolio that is diversified still makes sense. But you can still have fun around the edges.

Second, he only buys investments he understands. Wise words, but one that too many investors ignore. Last week the Financial Services Authority announced a clampdown on structured products, which have been flying off the shelves like hot cakes.The regulator said that many were so complicated that in nearly half the firms it investigated the advisers themselves did not understand how they worked. If you don't understand it, don't buy it.

But as a parting note, one Buffett trait that we probably shouldn't all emulate is his diet - his favourite meal, according to a Omaha restaurant, is a T-bone steak washed down with Cherry Coke. At 76 it looks like it has done him no harm. However, a more diversified diet is probably the best way forward for the rest of us.

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