In this methodology, the product development process is divided into iterations, which allows for a rapid and repeated testing of the working software.
In a market that is already saturated with solutions to a wide range of needs, you need to find your niche. Having validated your idea and analyzed your competition you should be able to establish the primary goal of your new tool.
The easier and more aesthetically pleasing the design is, the more users will try and continue to use your product.