I am going to make an android app and it will contain some listings. So for this niche how a person can generate $$$ ? I can generate leads by capturing email and other info of the user but any other ways? What kind of advertisement should be there while user is on the app and it should not be tacky so that's what I'm concern about. OVERALL I'm looking for the revenue model for this online listing thing was searching internet and BHW too, I got something about OLX and QUIKR but it was not that I want so thought to post. Anyone can guide ?