The success of your idea will depend on the competitive forces that you are facing in the industry. Michael Porters 5 Forces model helps you identify and evaluate these forces.
As soon as you know what kind of idea you will be working on, you should start learning about the competitive environment and let it influence your product and business model.
See guidelines in the video below.
Michael E. Porter: How Competitive Forces shape Strategy, Harvard Business Review 1979.
In the video below you can see the 5 Forces model explained: