Before you actually start selling, make sure there’s money to be made in your niche. Validation is a must so you don’t lose time and money bringing a product to market that no-one wants.
Step 1: Start out with clear ideas what and for whom you are making, i.e. the ideal use of your product
One product can be a solution for different problems so it’s important to decide what’s the focus. Also, your product can be an innovative alternative to incumbents and form a new niche of its own. An example would be Thinx period underwear.
As a product-oriented startup, you probably already have a very good idea: