This question is far too open-ended to answer. I would avoid a ad or data-selling business upfront. I would focus on a simple transactional business (i.e. they

This question is far too open-ended to answer. I would avoid a ad or data-selling business upfront. I would focus on a simple transactional business (i.e. they give you money and you give them a product or a service for a month), and learning about your market and why they care about what you're offering.