Hardly anything yet. Only been at it a month. There is a lot to learn, and getting those first hubs up there and then seeing what gets hit by searches and what doesn't is important.
If they do get hits, but no one clicks or buys then need to check what is wrong with them.
I'm now stopping writing for a while and revisiting my earlier hubs to make them better for searches, and better for monetizing.
It's a learning curve.