The key to building wealth is to have your money work for you. But how do you do this – especially when you don't have a fortune to invest?

Fortunately, you don't need to have millions (or even thousands) to start investing.  The following list reveals seven great ways to invest $100.    

1. Invest in real estate

That's right, you don't have to be a millionaire to become a real estate tycoon. You can start investing in real estate with just $100.

If you want to invest in real estate while making a positive difference in the world, check out  AHPFund. AHPFund purchases distressed mortgages and works with the homeowners to keep them in their homes – while targeting a 12% return for investors. The minimum investment is $100.

Honorable mention: If you have at least $1,000 to invest, explore the Fundrise eREITs for more diversified real estate opportunities.

2. Invest in individual stocks

Most of the time it doesn't makes sense to invest in stocks with just $100 because you have to pay $5-10 for every trade. This means that your stock has to increase in value by more than 20% before you actually see a profit!

This has changed thanks to the Robinhood app.

Robinhood allows you to buy individual stocks – and it's 100% free. This means that you can invest that $100 in multiple companies (if you would like) without paying huge trading fees.

Robinhood makes investing in stocks a reasonable way to grow your $100 investment.

For a limited time, Robinhood is offering A Richer You readers a free share of stock when they start investing through this link (worth $2-150+). This makes right now a great time to start investing in stocks!

3. Invest in mutual funds/ETFs

If buying individual stocks seems too confusing or risky – and you'd rather just let your money grow without your involvement, then start investing with Betterment or another robo-advisor.

Betterment lets you buy into a diversified fund with no minimum. What does this mean? If a single stock goes down in value, your money will still be safe because it goes up and down with the market as a whole. This significantly reduces the risk of investing.

For a low-risk and easy to use investment, use a robo-advisor platform to invest your $100.

4. Invest in startups and small businesses

Imagine if you had invested $100 in Facebook before it got big. Your investment would be worth tens of thousands.

Of course, startup investing is risky, but it can pay off if you do your due diligence.

If investing in startups sounds appealing, check out WeFunder and other equity crowdfunding site to find startups that fit with your investment interests. Some of these sites allow you to invest as little as $10 in a new company.

5. Invest in Bitcoin

Bitcoin is a digital currency that has grown in popularity (and value) over the last few years. In fact, if you had invested $100 in Bitcoin in 2011, you would be worth over $1 million today!  

Although Bitcoin is risky and there's no guarantee that it will continue to grow at past rates, it's definitely an investment with historically high returns.

The leading platform for buying/selling Bitcoin in the US is Coinbase. Right now, if you invest $100 in Bitcoin via Coinbase, they'll give you another $10 worth of Bitcoin for free.

6. Invest in your own blog or business

The wealthiest people in the world are those who have started their own business (or inherited money from those who have started their own business). If you don't see a big inheritance windfall in your future, but want to establish a significant amount of wealth, consider starting your own business.  

Although many business models require more than $100 – you can very easily start a blog for less than $100. Although many blogs don't make money, if you do your research and commit, it is possible to earn anywhere from $10k – $100k+ per month with a blog.

7. Invest in P2P loans

Peer-to-peer (P2P) lending is an idea with a lot of potential. Rather than paying high interest rates on credit cards, people can borrow money from others.

Although some people have earned 7-9% from the lending P2P lending platforms (LendingClub and Prosper), my personal returns have been about 1%  – leading me to replace this investment method with others listed above.

If you do decide to invest in P2P loans, just make sure to research each note you buy – as this will prevent you from lending money to someone who can't pay it back.

In summary

Even if you don't have a lot, the sooner you start investing, the sooner you'll be on the path towards financial security. Every $100 you save today could double in value in 8 years, and may be worth $1,500+ in 30 years.

So whether you have $100, or $1,00,000 – start investing! Future you will be grateful.

Then, find ways to improve your income by learning a new skill or starting a side hustle.