You deserve to enjoy retirement without worrying about running out of money. The only way to make that happen is with smart financial decisions starting early in your life.

Most people can make a few simple money moves that should leave them with plenty of money to enjoy retirement. Here are three habits to embrace early on that will make all the difference to your financial security in your later years.

Older lady sitting on couch with Social Security check.

Image Source: Getty Images.

1. Saving 15% of income

The old rule of thumb was that you should save 10% of your earnings for retirement. But life spans have gotten longer, the buying power of Social Security benefits has fallen, and experts believe it's more likely than not you'll see lower average investment returns ahead. So you can't just invest 10% anymore and be confident that'll support you.  

To make sure you have the funds to enjoy retirement without worrying, it's best to err on the side of saving 15% of your income throughout your working life. This requires more sacrifice, but if necessary you can work up to it by banking your raises and increasing your investment contributions a little bit at a time.

For some people who are barely getting by, saving this much will be impossible. But you can hopefully cut your budget as much as possible to save what you can now and work on improving your income over time -- perhaps with a side job or asking about advancement opportunities at work.

2. Avoiding debt

More seniors than ever are entering retirement owing a lot of money. That's a big problem because you'll need a larger retirement nest egg to cover your monthly bills. And some of your limited fixed income will also have to be paid to creditors. You don't want to take on a lot of debt you'll be stuck with late in life, so it's best not to make long-term financial commitments when nearing retirement age if you don't absolutely have to.

Going into debt at any time in your life can actually undermine your retirement savings efforts as well. Any money you're stuck putting toward interest is money that you can't use to build your wealth. Unless you need to borrow for a true emergency and have no other options, steer clear of taking on most types of consumer debt -- with the possible exceptions of a mortgage and student loans, since these types of debt can often increase your net worth when used wisely.

3. Investing in index funds that track the market

If you are good at picking stocks and want to spend the time necessary to research companies, and then keep tabs on your investments, you can (and probably should) invest in individual stocks. By doing so, you could potentially beat the market.

For most people, however, buying index funds is a better bet. Index funds that track the market's performance, like an S&P 500 fund, spread your money around a very broad mix of different companies so you minimize your risk. And, given a long enough time horizon, an S&P index fund has never been a loser; it's always provided an average annualized return of around 7%.

By investing 15% of your income throughout your career and choosing a low-fee index fund that's all but a sure thing, you can improve your chances of steady growth over time and hopefully end up with a nest egg large enough to support you in your later years.