I view social media platforms as tools, not toys, we use to document and communicate our value. If you are serious about personal branding and not just playing around, you should never post anything, anytime, anywhere that you would not be comfortable allowing anyone to view.
Be an open book online. You want people to examine you so that they can see who you are, what you are about, and how you might be able to help them address opportunities or solve problems that matter to them.
If you are opaque instead of transparent online, I think you send a mixed message about yourself and your brand. If you behave online as if you have something to hide, should you really expect people to trust you?
Don’t buy the bad advice. Forget about looking around to see what others are doing. Let good judgment and professionalism define your behavior, both in person and online.