Most financial advisors agree that the best approach to retirement planning is to start early and let your investments grow over time. Many Americans aren't following this advice.

In a 2014 national poll conducted by Bankrate, more than a quarter of survey respondents ages 50 to 64 said they had not started saving for retirement. Even worse, 28 percent of Americans have less than $1,000 in savings that could be used toward retirement, according to a 2015 study by the Employee Benefit Research Institute.

There are strategies for middle-aged Americans who find themselves playing catch-up on their retirement savings. The most important may be to simply start now. "Every day you wait, you make the problem worse. The sooner you get started, the easier it will be to make up for lost ground. You don't want to have the same regret five years from now that you have today -- wishing that you had started five years ago," says Ken Moraif, senior advisor at Money Matters and author of the book "Buy, Hold and Sell."

Here are eight more tips to help you get on track:

Accelerate your savings amount. Maximize your contributions to employer-based retirement plans. The annual 401(k) limits are $18,000 for 2015 with a catch-up contribution for workers 50 or older that adds an additional $6,000.

Power savings is the essential ingredient, says Danielle L. Schultz, certified financial planning at Evanston, Illinois-based Haven Financial Solutions. You may need to create a budget and spending plan to boost your savings amount. "Monitor your spending so you can catch sinkholes and places where money just leaks away," she says.

Consider downsizing. Take a hard look at your housing costs, which can be one of the largest expenses for those in retirement. A condo or townhome can be more affordable than the four-bedroom house where you raised the kids but is now a big empty nest. "Even if the mortgage is paid off, single-family homes still have repair costs, intermittent major upkeep costs and property and utility taxes," Schultz says.

That goes for your vehicle, too. Switch out the gas guzzler for something smaller and more efficient. "Downsizing isn't a defeat, but it's a very smart decision that will leave you less stressed in retirement and leave more to enjoy your new, work-free life," says Andrew Meadows, vice president at Ubiquity Retirement + Savings, a retirement plan provider in San Francisco.

Scale into retirement and work longer. Consider working part time or ask your employer to reduce your overall hours to extend the number of years you are still earning income. "With the rise of the 'gig economy,' there are many jobs that are part time, and these can augment income. If your profession allows teaching or consulting, it may be worth seeing a career counselor who specializes in second-career changers," Schultz says.

Consider new ways to build additional cash flow. If there's a real trick to retirement, it's creating cash flow, Meadows says. "Start thinking about ways you can earn additional revenue once you stop work. One of the most popular ways to do this would be rental properties. Even a small apartment you rent out could be enough to make the difference between just getting by and comfortable living," he says.

Don't take on additional debt. We live in a consumption-driven society with roughly two-thirds of the total gross domestic product stemming from consumer spending. High interest rates on credit cards aren't worth the trade-off. Think about wants versus needs. "Remember, millionaires buy luxuries last and paupers buy luxuries first," Moraif says.

Don't take risks and experiment with your future. "Waking up at 50 and deciding to learn to trade options or become a day trader using your retirement savings as your testing grounds is a fool's game," says Joshua I. Wilson, partner and chief investment officer at Dallas-area WorthPointe Wealth Management. "Don't expose your must-have money. Using your leftover time to go against pros is just asking to get slaughtered. Nothing is more intelligent that knowing your limitations."

Don't hold too much money in cash. You need to invest to make your money grow. Financial advisors recommend a mix of stocks and bonds. If you are uncertain as to what ratio could be best for you, consider looking at target-date retirement funds. One example, the Vanguard Target Retirement 2025 Fund (VTTVX), is aimed at workers with about 10 years remaining until retirement age. The asset allocation mix is about 67 percent stocks and 33 percent bonds. "Properly balance your portfolio for safety. Nothing is certain in this world, but a balanced portfolio gives you the best chance of protection against loss and possibility of gain," Schultz says.

Don't dial up the risk. Now isn't the time to experiment with trading or investment vehicles that you don't understand or that promise high returns. "If I had every dollar I'd seen an investor blow on undervalued closed-end funds with big yields that eventually blew up, I'd no longer have to save for retirement myself. There is nothing the market doesn't know about -- you didn't find the secret gold mine and short cut the riches in a publicly traded security," Wilson says.

If you do want to make more sophisticated investments, join an investment club where you can get a lot of experience with very little savings risk, Shultz says, adding: "Educate yourself, and you won't be hoodwinked by slick salespeople."

More From US News & World Report

• 13 Stocks to Buy to Bet on China
  

• 10 Ways to Invest in Driverless Cars
  

• 10 Healthy Health Care Stocks to Buy Now