I remember when I first joined Facebook many years ago, I started making posts and sharing random pictures and one of the first things I did was like my own posts. Then my friend told me that Facebook rule number 1 is that you shouldn't like your own posts. So do you ever like your own posts on Facebook?
Pardon me but I really find that silly. Yeah, I have lots of friends in Facebook who do that - they themselves are the first one to click the like button on their post as if that like can bring them something good. Anyway to each his own. And if they like to like their posts then so be it. But for me, it's unethical to like what you had posted.
I found it lame at start without it being a rule. I don't really use Facebook anymore, not to mention posting anything or liking stuff. I keep it up to stay in contact with friends and I play 1 game over it. That is all I do.
Yes I do like my own posts on Facebook. Not all of them, some. This helps to pull the post to the top of your activity and also help previous popular posts gain more views.