Anyone have some advice for me?

My boyfriend worked as a car salesman for a while now. He unfortunately had to leave for a year due to complicated medical issues. Now that he's back to work, he's lost the majority of his repeat customers and he's back at the bottom of the totem pole. I'm trying to help advertise for him, trying to get people to buy from him but I'm having some issues. Anyone you know work for the automotive business? I need some advice to try to boost his sales so we can keep our head above water..