By Jeff Reeves

Special to USA TODAY

For many Americans, money is a constant source of stress.

According to Money magazine, 70% of married couples argue about finances – and more than half the fights stem from what one spouse saw as a "frivolous" purchase.

Even teenagers who haven't left the nest stress about their finances. A study from H&R Block this year showed 58% of teens said their finances will be less sound than their parents.

Making good financial decisions isn't just about providing for the distant future; it's about cutting down on the very real worries you feel each day.

To help you get in control of your finances – and reduce your stress level – here are 10 stupid but completely avoidable mistakes you should avoid:

Spending more than you earn: Let's start with the stupidest mistake of all – not doing math correctly. If you spend more than you earn, it always catches up with you. This is not to say you have to pay for everything with cash; mortgages and student loans are a practical reality for the vast majority of Americans. Still, it's crucial to make a realistic budget and stick to it, so you live within your means.

Not saving anything: Intelligent people can disagree over precisely how much you need saved for a rainy day fund or to provide for comfortable retirement. But not saving anything, and living paycheck to paycheck? That's just irresponsible. Not only does it provide no opportunity for things such as buying a house, it naively assumes you won't ever need the money for a rainy day should something unfortunate happen.

Living in a place you can't afford: Most financial experts say you shouldn't spend more than one-third of your take-home pay on housing and related expenses. This is especially true for those who don't make much money, because other bills will quickly gobble up the rest of your budget. Think of it this way: If you take home $2,000 a month but spend half that on housing, you have $1,000 left to survive. That works out to $33 a day for all your food, gas and everything in between. If you stretch yourself too thin on your housing expenses, you will struggle to pay for everything else and may never be able to save.

Missing out on a 401k match: Every American should be saving for retirement in some way. If your employer offers some kind of 401k matching, a failure to save is an even bigger mistake. A 401k match is literally free money from your employer as a reward for something you should be doing anyway, so take advantage of it.

Failing to invest savings: Even if you are saving money for retirement, the hill you need to climb to provide for your golden years is daunting. Experts recommend eight to 10 times your salary saved come retirement – meaning that if you make $60,000 a year you'll need $600,000. Or put another way, if you're 35, you have to save $20,000 each year for the next 30 years if you plan on retiring at 65! That's simply impossible for most people, and the only way to reach that target is to put savings to work through investments. Consider that if you invest your savings at a modest 5% rate of return, you only need to save about $8,500 or about 14% of your salary to create that same $600,000 nest egg in 30 years. That's much more achievable and a heck of a lot less pressure.

Investing with greed or desperation: There are risks with any investments – particularly if you chase aggressive, short-term fixes. It's almost universally true that higher rates of return come with higher risk, and promises of instant profits through day-trading or house-flipping often prove themselves too good to be true. Keeping greed in check is crucial – but so is planning properly to prevent falling way behind. If you build up a good emergency fund and start planning for retirement early, you don't have to take big risks out of desperation for a quick solution to your money problems.

Tapping retirement funds early: If you are saving for retirement, it's tempting to think the money in your 401k or IRA is up for grabs for anything. Cashing out one of these retirement funds early can often come with steep penalties, eating into your hard-earned savings. In addition to the tangible loss of that money, there's the fact that you still need to save for retirement. Shifting the shortfall from one part of your budget to another is not a real long-term solution. Worse, any money taken out of your 401k or IRA could have been growing over time – so you don't just lose the money that's withdrawn, you lose the lost investment returns on that capital to boot.

Waiting too long for life or disability insurance: Life insurance companies aren't run like charities, and they set premiums based on the risk of payouts. It's only natural, then, that an older American has to pay a higher premium for life insurance. Why wait? The vast majority of folks can take out a substantial and very affordable life insurance policy in their 30s and cover their spouse and family into their 50s or 60s. The same holds true for disability insurance to protect your earnings on the job.

Failing to make a will: Along the same lines, a good will is a crucial part of providing for your family should tragedy strike. In most cases, a visit with a qualified professional for a few hours will ensure your family stays in control of any assets and avoids any harsh estate taxes – not to mention prevent any squabbling among survivors.

Following a cookie-cutter approach: Saving money is always hard and is always personal. Don't let other people's perceptions of what is "right" lead you astray. Some people think it's foolish to ever have a penny of debt, while other people take advantage of every 0% financing deal they can. Some people think it's a waste of money to eat out frequently, and others demand an annual beach vacation to maintain their sanity. The bottom line is that as long as you are honest about your personal financial goals and stick to a realistic and personalized plan, what other people do and think simply isn't important. Your life, and your finances, are unique.

Jeff Reeves is the editor of InvestorPlace.com and the author of The Frugal Investor's Guide to Finding Great Stocks.