Retirement planning is no easy task. Not only do factors like salary, debt and expenses all affect your ability to save, but there’s also no one-size-fits-all solution to realizing the vision of your golden years. Here are ten retirement mistakes you can avoid.

1. Having No Retirement Plan
   Not starting the retirement-planning process is one of the biggest retirement mistakes. First, you should determine what you want your future to look like and how much money you can realistically set aside. Then, find a plan that will get you there. Some employers offer 401(k) plans and pensions, though the latter is becoming less common. You can also open an IRA without an employer sponsoring the account. These products, which can offer greater returns and more diversification than a traditional deposit account, are effective ways to grow your nest egg.
2. Not Knowing How Much You Need to Retire
   If you’re nearing retirement, take a look at your current salary, add up your expenses — including medical costs in retirement — and meet with a financial planner to calculate how much you’ll need to retire and live comfortably. If you’re decades away from retirement, come up with a savings rate to determine how much you should deduct from your paycheck each month to put in your retirement savings account.
3. Not Increasing the Amount You Save After a Pay Increase
   A retirement savings rate is the amount of money you deduct from your paycheck toward retirement. For example, if you deduct $200 every month from your $30,000 salary, your retirement savings rate is 8%.
   It would help if you always increase your savings rate as your salary increases. Then, put 100% of your raise toward retirement — you know you can already get by on your current salary.
4. Not Taking Your Employer’s 401(k) Match
   If your employer offers to match your 401(k) contributions to a certain percentage and you don’t opt-in, you’re leaving free money on the table. So make sure to contribute at least the amount your employer matches each month.
5. Relying Only on Social Security Benefits
   Social Security can provide some financial security, but you shouldn’t rely only on your Social Security checks to fund your retirement. According to the Social Security Administration, Social Security benefits represent about 39% of older people’s income. Trying to retire only on Social Security has a lot of hidden costs and risks.
6. Cashing Out Your 401(k)s Between Jobs
   According to Fidelity Investments, the average cash-out amount of a person under 40 who is changing jobs is $14,300. Although cashing out your 401(k) might seem like a good idea if you need to solve a short-term financial crisis, doing so can have dire consequences. For example, if you cash out or withdraw money from your 401(k) early — before age 59 1/2 — you could be hit with tax penalties. Along with any applicable federal and state income taxes, you could face a 10% early withdrawal penalty. Moreover, Fidelity reports that your 401(k) plan administrator will typically withhold 20% of your balance to cover the taxes. Therefore, rolling over your 401(k) is a much better option.
7. Assuming You’ll Want to Work During Retirement
   Although you can work full-time or part-time during your golden years, you might find that this option isn’t realistic. For example, your health could deteriorate, or you might just decide you’d rather travel or spend time with the grandkids. For best results, build a hefty retirement nest egg if you realize working during retirement is not the ideal option.
8. Not Using a Retirement Account That Offers Tax Benefits
   Instead of using a traditional savings account to save for retirement, you should be using a retirement account that offers tax benefits, such as a traditional IRA, Roth IRA, or 401(k). These retirement accounts can also help you save on taxes, so take advantage of them now.
9. Not Picking the Right Investments
   Whether you’re investing in the stock market through a 401(k) or independently with the help of a financial advisor, make sure you’re making suitable investments based on your risk profile. Your retirement portfolio can survive through stock market fluctuations and volatility. Your retirement portfolio should include a healthy mix of stocks and bonds — including short-term, long-term, large-cap, mid-cap, small-cap, and international — and even cash investments. Review your investments and allocate assets as needed to diversify your retirement portfolio.
10. Retiring Too Early
    Retiring early has two main disadvantages. First, the earlier you retire, the less time you have to save for retirement. The second disadvantage has to do with your Social Security payouts. Although you can retire as early as 62 and start receiving Social Security benefits, your age dictates the size of your payout. For example, if your full retirement age is 67 and you start your retirement benefits at 62, prepare for your monthly benefit amount to be reduced by about 30%.

Reference
https://www.gobankingrates.com/retirement/planning/common-retirement-planning-mistakes/.