In 2019, everything is online. If you need any piece of information, the simplest way to get it is to type it into Google and scroll through some results. For example, you can Google someone's name and have photos of them, links to newspapers they were mentioned in, and all of their social media accounts right at your fingertips. This may seem a bit extreme, but just try searching for your own name and see how much comes up about you (especially if your name isn't very common).
Recently, Netflix released a show called "You" in which a young man who works in a bookstore stalks a patron until she loves him. He knows exactly where she lives, where she works, what she likes to do, and who she spends her time with all by doing some basic online searching. As soon as he types in her name (which he gets from the credit card that she used to purchase a book from his shop), all of her information appears for him.
Based on this, the first step you should take is never using your full name online. There are a ton of "Johns" in the world, but far fewer "John Smiths," so making this change to your accounts will make it much more difficult to find a specific person. It is pretty safe to use your first name, but beware if you have a very unique one, as this can also make it easy for someone to find you. In that situation, it is probably best to use a nickname, because that will be even harder to identify as a specific person.
Although it should be common knowledge, do not post pictures that have a clearly visible address of your home or workplace. It can be easy to not look for details like this when posting a family photo outside your home, but it could put your safety at risk. Make sure you do not tag photos to your workplace or home address, and for good measure, don't post your friends or family's personal information online to protect both of you. If someone really did have poor intentions, they could mistake your aunt's house for yours and show up there.
If you are very concerned, it may also be a good idea to set your accounts to private and manually approve who can see your information. This can be time-consuming on websites like Facebook, or very simple on websites like Instagram, depending on how personal you want to keep everything. On Instagram, you simply put your account as private, which requires you to approve each person that wants to follow you and limits your posts to only those people, whereas Facebook has settings for anything you could imagine, and you can be as specific as you want with who can see what.
The name of the game is keeping a clear separation between your personal information and your life online. In most aspects, it is not a good idea to keep a fake persona up for your followers, but when it comes to sensitive information that would be dangerous to have out in the open, it is what is best.