When someone buys an item ogg me i always contact them and thank and appreciate there purchase etc ... and few other nice things, i found i get people happy to come back and buy again if the item was good with great communication. 

Also normally after about 1 month people that have not left me FB i kindly thank them again and ask nicely if they dont mind putting FB as it means so much to other buyers and most will when they see my message

Have a great Christmas all 🙂