Couple with accountant © Ryan McVay, Photodisc Red, Getty Images

Financial plans are only for people with so much money, they don't know what to do with it, right?

Actually, studies show that a comprehensive financial plan can benefit people at all income levels -- but not a lot of Americans know this.

Only 31% of financial decision makers in families say they have created a comprehensive financial plan either on their own or with professional help, according to the 2012 Household Financial Planning Survey conducted by the Certified Financial Planner Board of Standards. The Board defines a comprehensive financial plan as one that covers savings and investments; planning for retirement, education, emergencies, major purchases, and other financial goals; and insurance needs.

But few people have plans in place to cover even a part of their finances: The same study showed only 35% of people have a plan to save for emergencies. And only two-thirds have a plan to meet any of six savings goals, such as for emergencies, retirement, a child's education or a down payment on a house.

It's too bad those figures aren't higher, given that the same survey showed that comprehensive financial plans benefited even people at lower income levels.

As Tom Pemberton, a certified financial planner and owner of Charlotte-based DBA Pemberton Financial Planning, said, "The way you get into the higher income bracket is to have a financial plan."

And don't dismiss financial plans as being for older people. Pemberton, in fact, recommends financial plans for people in their 20s, to help prevent them from making financial mistakes.

"If you look at people who are financially successful," he said, "most of them have been making very smart financial decisions all their life. The sooner you start making smart decisions, the sooner you know where you want to go, and if you have a plan to get there, the more likely you are to attain it. Time is the one thing nobody can give us. If you start in your 20s, you don't have to save that much. The longer you wait, the more you have to save to make that goal." (He was referring to the fact that, the more time investments have to grow, the less money an individual needs to put away in order to achieve the same returns as someone who gave their money less time to grow. This principle is especially helpful for long-term savings goals such as retirement.)

Here are 10 reasons to get a comprehensive financial plan if you don't have one yourself:

1. It will help you define your financial goals

Most financial planners will begin your plan by asking you what your financial goals are. For couples, sometimes doing this exercise alone is enough to get the two partners on the same page. "Most people spend more time planning their vacation than planning for retirement or for their financial goals," said Pemberton.

2. It will help you see whether your goals are realistic, especially for your timeline

After taking a look at the goals, Pemberton looks to see how you can get there -- how much to save, what types of investments to make. "Then, the planner can do a cost-benefit analysis. Are your goals realistic? Are they attainable? Most of us have more goals than financial resources," he said, adding that time is a huge factor. "It's usually not that the goal is not attainable, it's that the timeline is not attainable," he said, noting that many goals, such as saving for retirement, a mortgage or a child's college education and paying off debt, take years to accomplish.

3. It will help you see how you can bring your spending in line with your goals

Once you know where you're headed and how long it will take to get there, then you can look at your cash flow to find out if you're spending more money than you're taking in. "If you have negative cash flow, there's no way you can meet your goals," said Pemberton. The exercise of analyzing expenses often surprises people. "They say, 'I had no idea I was spending that much on Starbucks (SBUX) or eating lunch out,'" he said.

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4. It will show you what money mistakes you're currently making

Aside from spending too much, Pemberton says analyzing not just spending but the overall financial picture sometimes exposes mistakes -- and easy fixes. Pemberton said, sometimes people look at their credit card debt and say, "I'm paying 18% on interest to a bank. Am I making anywhere near 18% on any of my investments?"

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