Talk to any Keralite or Bangaldeshi as they dominate the small cafeteria business in Doha. They will advise you best. I can just give you a tip. In this business, nationality really counts. For example if you are from Bangladesh, Muaither or Sailiyah will suit your business best as the entire area is infested with Bangladeshis. A Keralite will rarely go to a Bangladeshi restaurant.