There always seems to be a fine line that you walk at work with what you can share and what maaaaaaybe you should just, you know, not. All of this depends on the culture of the organization as well and the relationships that you build with your co-workers, plus your own personality. Some people are more willing to chat and talk about things while others like to feel things out first. This article from LearnVest though kind of sets the tone for a few things that you should really just not talk to your boss about. And really, they are pretty basic/common sense. Obviously you never tell you boss that something they are asking you to do is impossible. If something is difficult or you don’t think that you can handle the task, think about reframing your concerns. Flat out saying no way this is impossible and I’m not going to do it…just doesn’t go over as well.
The other thing to keep in mind is your personal life. Often times, our professional lives and personal lives will meet and possibly bleed into each other. Sharing a bit about your personal life helps you also establish relationships (and dare I say friendships) at work. But there is appropriate to share and then there is not appropriate. No one needs to hear how hungover you are (heeeey college kids, same goes for you) or what insane drama is happening in your life that is making it hard to concentrate at work.
Again, what is appropriate and not appropriate at work really depends on a number of things. I have had bosses that have barely known my last name and I had a supervisor who I actually ended up living with in grad school. My general rule of thumb, don’t overshare. Air on the side caution. You can always let more people into your personal life but you can’t undo saying things that you have already said.