Use a REIT
There are many ways to earn a little extra money. One such way, especially if you don't have the time or resources to heavily invest in real estate, is to instead invest in a REIT.
Keep in mind that some REITs invest directly in real estate, while some invest in mortgages, or mortgage securities. Consult with the REITs, to find out what they invest in, and if it lines up with your goals.
This is also another good source, with many over 10.%