You can only have 2000 or 3000 friends, or what ever it is.
The key to FB is joining Facebook groups made up of people that relate your art.
And don't make the mistake that a lot of people make in only befriending other artist and join only art related groups. Those people are not really buying that much but they are all selling.
I am not saying that friends are not important. Every set of eye balls are important. But a couple few thousand is not enough. I reach a potential of 3 million people, even that is not rough as far as I am concerned..
I would also suggest that you only post links to you ArtistsWebsite and not to your presence on Pixels or FineArtAmerica. One two clicks and those visitors are gone, lost in sear of over 2 million images.
Don not do use the automatic post that is available via FAA either. Post you images directly to your own page with links back to those exact images on your ArtistWebsite.
Have fun and best of luck to you.