Women tend to live longer than men, and also tend to have less money to live on in their later years. There are lots of reasons for that, including the impact of the gender wage gap on retirement savings. Some are difficult to correct, but there's one simple way women are falling short that's easy to fix: They're far less likely than men to have a written retirement strategy. 

According to recent research from the Transamerica Center for Retirement Studies, just 19% of women have a written retirement plan compared with 34% of men. This may not seem like a big deal, but since not knowing where to start is a leading obstacle to retirement savings, the process of making a written plan can make a world of difference in retirement readiness. After all, doing it forces you to determine the amount you need to save and set concrete goals with a timeline for achieving them. 

The good news is, it's not hard to make a plan. Just follow these five simple steps. 

Woman looking at notebook with calculator and computer.

Image source: Getty Images.

1. Determine when you'd like to retire

The first step in making a written retirement plan is to identify when you'll likely leave the workforce. This tells you what your Social Security benefits will be, what your deadline is for building your nest egg, and how long your money will need to support you. 

When considering your retirement age, err on the side of retiring earlier rather than later. While many people plan to work well into retirement, few actually do. If you assume you'll retire and claim Social Security at 62 -- the earliest possible age you can -- you'll be in good shape to leave work then if you must. If it turns out you can work longer, you'll simply end up with some extra money. 

2. Identify the amount of money you'll need to save

Next, you'll need to figure out how much money you'll need as a retiree. There are several approaches to doing this calculation, but one of the easiest is to figure out your final salary and assume you'll need 10 times that amount. If you're 20 years away from retirement, assume a 2% raise each year from now until you leave the workforce to calculate your final salary, and then multiply that amount by 10. 

3. Calculate the monthly amount to invest to achieve your goal

Once you've got an idea of how large your nest egg needs to be, it's time to break that big number down so you'll know what to save each month to achieve it. There are lots of online calculators that can help you do that. 

Setting a monthly goal makes it possible to work retirement savings into your budget and, ideally, to automate your investments so money is transferred right away to your investment account.

4. Outline your investment strategy

Investing your money can help you hit your retirement target because your invested funds will work for you. But you want to minimize the risk associated with investing -- and developing a comprehensive strategy is the best way to do that. 

First and foremost, you'll want to identify the right tax advantaged accounts for retirement savings.  Options could include a workplace 401(k), an IRA, and a health savings account (HSA) if you're eligible to contribute to one. You'll also need to make sure you're building a diversified portfolio that exposes you to the appropriate level of risk. Generally, you'll want to subtract your age from 110 to determine the percent of your money to put into stocks and then invest the rest in bonds or another low-risk asset. 

Finally, you'll need to decide if you want to try to beat the market by selecting individual stocks or would prefer to take a simpler approach using ETFs. If you're investing in a 401(k), you'll have fewer options, so if you'd prefer to buy shares of individual stocks you'll likely need to put some money into an IRA too. 

5. Track your progress

Finally, you'll want to keep tabs on your progress and make sure you're following your written plan and are on track to achieving your goal.

By taking these steps, you can make sure you're well-prepared for retirement. And it's not just women who should take them -- although of course women owe it to themselves to be just as likely to make a written plan as men. The reality is, no matter your gender, a written retirement plan is a must to prepare for your future.