When you finally get a moment of free time, you probably don't want to spend it reading prospectuses and reallocating your retirement funds. But ignoring your retirement accounts completely can lead you dangerously off track. If you want a hands-off retirement plan, you should take the following two steps first.

1. Invest in a target-date fund

Target-date funds are bundles of investments you purchase together. These funds often have a year in their name, which represents your target retirement year. Their asset allocation automatically grows more conservative over time to help you protect your growing nest egg.

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Each target-date fund has its own mix of investments and varies in how quickly its asset allocation changes. This is known as its glide path. Funds with a "to" glide path hit their most conservative asset allocation in the target retirement year, while funds with a "through" glide path continue to grow more conservative after the target year.

Choosing a target-date fund means you don't have to personally worry about adjusting your asset allocation over time. This can be reassuring for those who don't feel confident picking their own investments.

But target-date funds aren't always the most affordable options. If your aim is to keep your costs as low as possible, you'd do better to invest in index funds or other investments, and adjust your asset allocation yourself over time. 

If you decide to invest in a target-date fund, you can find them with just about any broker. Many times, they're available through 401(k)s as well. First, decide when you plan to retire so you know what target year to look for. Then, compare the fees, investments, and glide paths of each one to decide which you'd like to invest in. You can find this information in the prospectus, which is often available on the fund provider's website.

2. Use dollar-cost averaging

Dollar-cost averaging is investing money on a set schedule. You might invest $100 every week or $500 every month. It's up to you. If you have a workplace retirement account, you're probably doing this already. But you can also use this strategy with many IRAs and taxable brokerage accounts.

You may have to set up an automatic transfer from your bank account to your investment account. To do this, you'll need your bank's routing and account number. You'll also need to decide how much you want to transfer and over what time period.

Using dollar-cost averaging eliminates the risk you'll forget to make retirement contributions on your own. It can also reduce the likelihood that you'll make emotional investing decisions because you won't need to check your portfolio as often.

Dollar-cost averaging may not always score you the best price, though. Sometimes, you'll buy when prices are high and you won't get as many shares. But other times, you'll buy when prices are low. Over time, it averages out and helps you stay calm through the market's ups and downs.

But you don't want to be too hands off

Investing using the two strategies above can take a lot of the work off your plate, but you still need to check on your investments at least every year and whenever you experience a major change to your finances. Look over your investments and your contributions, and decide if you need to make any changes.

If, for example, you've decided to delay retirement, you may also want to change to a different target-date fund or other investments that are better suited to your new timeline. Or if you've recently gotten a raise, you might want to boost your retirement contributions.

It's important to make changes promptly when necessary. The longer you wait, the more difficult it is to make up for lost time. By building an annual retirement-plan review into your strategy, you can reduce your risk of winding up way off track.