When it comes to savings, Americans are falling short. Nearly 70% of adults have less than $1,000 in their savings accounts. Retirement funds are looking equally bleak. In fact, about half of US families have zero retirement account savings. "Particularly the younger generation likes to think, 'I'll save more when I'm making more.' But whether you're making $50,000 a year or $200,000 a year, we all have challenges saving," says Kimmie Greene, money expert at Intuit and spokeswoman for Mint.com. "Because oftentimes what happens is, when people make more," she says, "they end up spending more."

The sooner you start saving — for retirement or any other major purchases you hope will be in your future — the better. After all, time is on your side when you're young, thanks to the power of compound interest. While the amount you need in savings is highly personal, and specific dollar amounts can be arbitrary, Greene offers a simple formula to help you figure out if you're setting aside enough money. In your 20s: Aim to save 25% of your overall gross pay, Greene tells CNBC. "That 25% is the combination of 401(k) withholdings, matching funds from your employer and any cash savings that you have," she notes. "It can also include debt repayment. "Just make sure your lifestyle expenses don't exceed 75% of your gross income." By age 30: Have the equivalent of your annual salary saved, Greene says. If you earn $50,000 a year, aim to have $50,000 in savings when you hit 30. Again, this includes any retirement account contributions, matching funds from your company, cash savings, or money you have invested elsewhere, in index funds or robo-advisers.