Martin Graham, chairman of London's Oracle Capital Group, knows a thing or two about millionaires.

His wealth consultancy firm manages several billion dollars for about 40 European families, most of whose fortunes were built by self-made entrepreneurs.

'They're brilliant at running their company, but may not be brilliant at handling their own money,' said Graham, who is also a former director of markets for the London Stock Exchange.

The goal of most millionaires is twofold: to keep getting richer, and to protect the riches they've already earned.

The good news for the more modestly heeled consumers out there is that the super-wealthy don't have any secret skills that the rest of us can't imitate.

We asked Graham to share a few guiding principles that anyone -- whether you make $50,000 or $5 million -- can use to better manage their money.

1. Only invest money you have for the long term. Unless you've got a nice stash of emergency funds on hand, you have no business meddling in the stock market. Here's the rule of thumb Graham typically goes by: 'Don't invest money that you can't lock away for five years.'

2. Don't invest in anything that you don't understand yourself. When it comes to investing, individuals often have an edge over the professionals, Graham said. For example, when famed British retail chain Marks & Spencer brought in new product lines and lost touch with customers in 2012, it wasn't stock analysts who picked up on it first. 'The man on the street knew that,' Graham said. 'You should invest in things you understand because the experts can get things wrong.'

3. Don't sit on your investments for too long. We've all heard it before, but Graham emphasized the need to diversify your investments, both by location and industry. It's important to have some downside protection in the markets world, and you probably will need to shift around investments on occasion, he said.

That doesn't mean spending hours a day trading obsessively or trying to beat the market. Prepare a plan with a financial advisor on how often you should rock the boat. 'Be prepared to rebalance your portfolio to get the best returns from time to time, ' Graham said, especially as you age and are less willing to take risky bets with your nest egg.

4. Go against the crowd. The markets -- and the media that follow them -- aren't always right.

Gold was everyone's investment du jour a year ago, and now it's tanking faster than the Titanic. And who could forget the dot-com boom of the early '00s and 2008's crippling housing crisis.

Don't be afraid to buck the trend and invest in things that aren't getting all the attention sometimes. 'You need to be brave to buy against market sentiment,' Graham said. As always, follow the golden rule of buying low and selling high.

5. Prepare for a rainy day. The no. 1 goal of the rich is to protect their wealth at all costs.

'A lot of our clients are interested in preserving wealth for future generations,' Graham said. That means making sure that they are prepared for any business or personal circumstances that may pose a threat. For most people, that could be as simple as losing a job or going through a divorce. You could invest all day in the market or buy up a chunk of cheap real estate, but without liquid assets to depend on in leaner times, you won't get far. (Not yet a millionaire? See our Million Dollar Savings Calculator to learn exactly how soon you can earn your first million.)