In October, a Japanese man was accused of stalking and assaulting a young pop idol. What makes this news shocking is the details of how he found out where she lived.

“All a stalker needs to find your whereabouts is pictures from your social media accounts,” says Daniel Markuson, a digital privacy expert at NordVPN. And some people upload a great number of them every day without even a thought about possible risks.

The Japanese stalker told the police that his victim’s photographs had helped him identify the exact train station she would commute from. He would zoom in on her selfies and analyze the scenery reflected in her eyes. Then, he would study her online videos to determine in what building and on which floor she lived.

The case demonstrates the great issue social media users face these days — digital stalking that may outgrow into physical harassment. Markuson says: “Although collecting likes and reactions on your photos makes you feel good, the backgrounds of these images also send signals to criminals lurking online.” These might be stalkers acting on uncontrollable feelings for their victims or burglars looking for new targets with luxurious lifestyles.

The digital privacy expert provides some tips on how to protect yourself and your pictures online from criminals:

1. Make sure to set your account preferences to private. Before posting anything online, check who you’re sharing the information with. Make your posts visible to your friends only instead of everyone on the internet.

2. Don’t connect with strangers on social media. Before befriending someone you don’t know on Facebook, go through the mutual friends’ list or things you have in common.

3. When browsing online, always protect your location. Keep your whereabouts private by using a reliable VPN such as NordVPN. The virtual private network will hide your IP address and real location. By connecting to another country’s server, you can set your location to virtually anywhere in the world.

4. Don’t upload high-resolution pictures to your social media profiles. It’s very easy to download a Facebook picture to a computer. Make sure to hide all house numbers, street names, or other information that can indicate your whereabouts.

5. Make sure you’re not oversharing. Revealing too much information is never a good idea, especially online. When signing up for a social media network, never put your home address. Don’t post pictures of any documents or tickets.

6. Don’t tag any locations around your home on your online pictures. Also, you can turn off geotagging so that no location-disclosing metadata is added to your photo files.

Even if you think you’ll never be a target of an online stalker, you may become one someday. To avoid potential risk, stay alert and don’t reveal too much.