The retirement dream is moving out of reach for many Americans. A quarter of baby boomers expect to postpone retirement until age 70 or beyond, according to a report from the Insured Retirement Institute, and 8% don't think they'll ever retire.

Even if you're doing everything you can to scrape together some cash to put toward your retirement fund, saving for the future isn't easy. The average American thinks retirement will cost around $1.7 million, a survey from Charles Schwab found, and one in 10 thinks they'll need at least $3 million to retire comfortably.

Although it can be difficult to save for retirement, there are few things that may be making it harder than it should be. These mistakes may seem harmless at first glance, but they have the potential to derail your entire retirement plan.

Broken piggy bank with coins falling out

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1. Helping children with student loans rather than saving for retirement

More than half (53%) of parents say that helping their children pay for college is a bigger priority than saving for retirement, according to a survey from T. Rowe Price, and 68% are willing to delay retirement to help pay for college tuition.

There's nothing wrong with financially helping your kids if you can afford it, but putting your own financial needs on the back burner can potentially lead to disaster down the road. Saving for retirement isn't something that can be done overnight, or even over a decade or two. Unless you have thousands of dollars to put toward your retirement fund each month, you'll likely need to start saving several decades before you plan to retire.

For example, say you want to retire at age 70 with $800,000 saved. You're currently helping your kids pay for college, so you hold off on saving for retirement until age 45. To reach your goal, you'd need to save approximately $1,100 per month, assuming you're earning a 7% annual return on your investments. But if you'd started saving at age 30, you'd only need to save around $350 per month.

It can be tough to strike a balance when you have multiple financial priorities pulling your wallet in different directions. But the longer you wait to start saving for retirement, the more difficult it will be to catch up. That's not to say you can't help your children with college, but if you ever want to retire, you can't forget about your goals, too.

2. Not paying off high-interest debt

Debt in any form can be a strain on your budget, but high-interest debt in particular can wreak havoc on your financial health. Depending on how much debt you have, you could end up paying thousands of dollars in interest alone, and it could take years to pay off your debt completely.

In most cases, it's a good idea to start saving for retirement as early as you can. If you hold off on saving for years until your debt is completely paid off, you'll have to work significantly harder to save enough to retire. However, if you're saddled with loads of high-interest debt, you could be paying more in interest than you're earning on your investments. Especially if you have credit card debt (with some cards charging interest rates upwards of 20% per year), even a solid 7% to 8% rate of return on your investments may not outweigh what you're paying in interest.

In that scenario, it may be wise to pull as much cash together as possible and pay off your high-interest debt as quickly as you can. Begin with the debt with the highest interest rate (not necessarily the highest balance), and then work your way down. Once you're left with only lower-interest debt (like a mortgage or student loans), you'll likely be able to go back to saving for retirement.

You may still need to jump-start your retirement savings to catch up once you pay off your debt, but once you're no longer paying an exorbitant amount in interest, you'll have more to save each month.

3. Not having an emergency fund

An emergency fund is a crucial yet often overlooked factor that can help you save more for retirement, yet only 61% of Americans have enough cash saved to cover an unexpected $400 expense, according to a report from the Federal Reserve Bank.

If an unexpected cost pops up and you can't afford to cover it, you'll either need to rack up credit card debt, take out a loan, or tap your retirement accounts for cash. Going into debt has its financial consequences, and borrowing or withdrawing cash from your retirement fund can potentially cost you thousands of dollars over time.

More than half of Americans have withdrawn money from their retirement accounts for reasons other than retiring, a survey from MagnifyMoney found. But withdraw from your 401(k) or traditional IRA before age 59-1/2, and you may be subject to a 10% penalty fee. You also could be missing out on thousands of dollars in potential future retirement savings, even if you only withdraw a small amount.

Compound interest -- which is essentially when you earn interest on your interest -- helps your savings grow exponentially. The key, though, is that your money has to sit untouched for decades to reach its full potential. When you withdraw or even borrow from your retirement fund, you're missing out on valuable time to let your money grow, as well as making it harder to reach your savings goals. But if you have an emergency fund to cover unexpected costs, you won't have to worry about dipping into your retirement fund to make ends meet.

Everyone makes mistakes, especially when it comes to retirement planning. However, some mistakes are worse than others, and the worst offenders can cost you thousands of dollars. But by avoiding these common mishaps, you can keep your retirement planning on track and make sure you're doing everything you can to set yourself up for success.