5 retirement tips that actually work, from people who used them to retire happily years ago

Saving for retirement is something that should come long before you start thinking about leaving work — for many people, it's a lifelong process. 

But it can be difficult to know just where to start when it's far off. Luckily, plenty of people who have retired are willing to share their advice, and many have shared their tips with Business Insider. 

Here are five money rules that have helped retirees have a happy and financially secure retirement.

1. Start saving 15% of your income while you're young

Financial planner and writer Chloe A. Moore shared the retirement advice her uncle used to retire at 56. His first piece of advice was to "save early and save aggressively," she writes. He starting saving right after college, and aimed to put away 15% of his income.

"I followed in his footsteps, and those early days of saving put me well ahead of my peers by the time I was 30," writes Moore.

Saving for retirement works best when start young — retirement savings rely on time and compound interest to grow. And even saving 10 years sooner can make a big difference.

Here's an example that shows what happens when two savers start saving $100 per month at ages 25 and 35, both with a 5% rate of return. 

The saver who started at 25 contributes $12,000 more of their own money, but saves $162,000 total. Meanwhile, the saver who started at 35 ends up with almost half that, with $89,000 in their account. With retirement savings, starting sooner is always better.

2. Invest in rental properties for future income

When her parents retired, writer Donna Fenn witnessed firsthand how rental-property income can provide security in retirement. Her parents owned two rental properties; in one, they lived on the bottom floor themselves for years. Owning these properties was important when both of her parents retired, and especially after her father died.

"Those houses, which have been mortgage-free for many years, provide my mother with an important source of recurring income," Fenn writes.

While her mother now lives in an assisted-living facility, they could be important income for her care later.  "If she outlives her [long-term care insurance] benefits, the sale of those assets or a home equity loan will yield enough cash to keep her comfortable," she adds.

3. Treat debt as a last resort, even while you're still working

Writer Choncé Maddox learned to be frugal and treat debt as a last resort from her father-in-law, who retired at 63.

"My father-in-law often steers clear of things he can't buy in cash. If he absolutely can't pay cash, he'll make a sizable down payment," Maddox writes. "My in-laws always buy used cars in cash. They've saved hundreds per month by not having any car loans, and that's over the past 20-plus years." 

For many retirees, a debt-free retirement is a key way they make their life affordable. Paying down debt before retirement can help lower your monthly obligations, and free up limited income for other goals. Staying out of debt when you're young is key, too, since it frees up cash you can stash away in savings or a retirement account.

4. Think long-term when you're making financial decisions

When writer Robin Kavanagh's parents retired 10 years ago, they were faced with several choices for her father's pension. "He could either take a lump sum of money, receive a larger amount monthly for the rest of his life, or a smaller amount monthly for the rest of both his and my mom's lives," she writes for Business Insider. 

Her parents opted for the choice that would provide the benefit the longest, opting for the smaller amount paid out over both their lifetimes. "My parents opted for the smaller pension payment so that they would have another stream of assured income for life," she writes. 

Like many other decisions in retirement planning, taking the long view is the best move. Questions like when to take Social Security require this mode of thinking — the sooner you take the payments, the less benefit you'll receive each month.

For Kavanagh's parents, the long term was the priority, and it paid off for them. "As it stands now, that income plus their Social Security payments cover their day-to-day living expenses," she writes. 

5. Factor your retirement into every single financial decision you make

For most people, saving for retirement is a lifelong process. When writer Olivia Christensen asked her grandmother how she saved enough to live comfortably in retirement for more than 20 years, her answer was simple: "Factor your retirement into every single financial decision you make."

 Her grandmother, Ellen Young, made the decision to make paying off her home a priority. "She made as many extra payments on the mortgage as she could to pay down the principal. There were two layers to this retirement strategy: First, by paying down the principal as quickly as possible, she saved thousands of dollars on interest. And second, by eliminating debt, she alleviated her future retired self from making sizable monthly payments," Christensen writes. For her grandfather, it meant choosing a job that came with a generous pension package.

Young tells Christensen that starting early was one of the keys to her success. "You can't work forever. You have to retire, so you need to plan for it."