Rainbows are likeable.
What is it about rainbows? I pulled over to take the photo above and post it to my Facebook page. Grown-ups were pointing and staring at it/ them (if you look carefully you’ll notice that it’s a double rainbow).
For me, I think that they’re a sign that we live in a world of wonders. And we find that inspirational. And, very likeable- as the photo got 33 likes.
Do you pay attention to what gets the most likes on your personal or business Facebook page? Most research shows that photos are usually involved. And/or something that causes an emotional pull (see Contagious: Why Things Catch On by Jonah Berger for even more information about what causes things to ‘go viral’).
My latest post on Facebook was photo-less but still got a lot of likes: ”First time I have ever had to wait in line for the women’s bathroom at Wharton exec ed. I am so happy that there are that many women here!” (23 likes). Also, emotional and inspirational 
Check your posts and see how they rate on emotion and inspiration. See if you can add a little more to them as you test what works best for your tribe.