Real estate investment trusts (REITs) have grown increasingly popular over the past decade -- for good reason. These companies, which invest in real estate and real estate-related securities, are required to follow strict rules when it comes to their holdings, including paying 90% of taxable income in the form of dividends to shareholders in order to benefit from certain tax advantages.

This means REITs' unique structure can offer investors higher-than-average dividend payments, diversification, and exposure to high-quality real estate investments that would otherwise be inaccessible. Historically, REITs have outperformed the S&P 500 over the past 20 years, with last year's return for all REITs, as tracked by the National Association of Real Estate Investment Trusts (Nareit), close to 16 percentage points higher than the S&P 500 return, at a whopping 29%. 

When it comes to real estate investing, there truly is no other investment strategy that offers the same ease and accessibility as investing in REITs. If you're looking to expand your portfolio by investing in REITs this year, here are three easy steps to get started.

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1. Open a brokerage account

Most investors choose to invest in publicly traded REITs because of their ease of investment, which is done by purchasing shares in the company through a brokerage account. Although there are over 875 private REITs to choose from as well, the investment process will look very different from investing in public companies.

If you're just getting started, I suggest sticking to publicly traded REITs until you gain more experience, which means you'll need to open a brokerage account if you don't already have one. A brokerage account is used to invest in and trade securities, including stocks, bonds, index funds, or mutual funds.

There are a wide variety of brokerage platforms to choose from, many of which offer great low-cost incentives like no monthly minimum, flat-rate trading fees, and no costs or minimum balance needed to open an account. However, it's important to compare the different platforms before signing up. Assuming there is no minimum balance to open your brokerage account, you can transfer as little as a few hundred dollars into the account and start trading.

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2. Choose what REITs and industries to invest in

There are more than 225 publicly listed REITs to choose from, in every real estate industry sector, making choosing which REIT to invest in a challenge. As a new investor, equity REITs, which are REITs that invest in physical real estate, leasing them on short- or long-term leases, are the safest option.

Most equity REITs invest in a single sector, which include: 

However, there are diversified REITs that own a mix of the properties in the industries above, as well as mortgage REITs (mREITs) that invest or originate mortgages for commercial or residential property.

Since REITs are directly invested in real estate, there are additional factors that can impact performance outside of market volatility, meaning it's important that investors educate themselves on the risks and opportunities within the respective industries.

The Motley Fool is a great resource on which companies are worthwhile buys today, including which REITs have the highest growth prospects or most reliable returns and dividends, as well as which REITs to avoid.

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3. Purchase shares in the REIT

This may seem obvious, but once you've identified which REITs to target, you simply need to purchase the desired number of shares in the company -- in other words, buy the stock. How much you purchase will depend on how much you have to invest, but aim to own anywhere from one to 10 different companies across a few different industries. It's a good idea to diversify your portfolio by never putting more than 10% of your investment account into any one company, and it can be advantageous to build your portfolio slowly over time rather than diving all-in at first. 

As with any investment, there's always risk, but if you hold your portfolio long term and carefully select your REIT investments, looking at the company's past performance, future growth opportunities, and current operations, there's a strong chance your investment will pay off handsomely.