Confirm money is already moving in the category, pick the fulfillment model, and pressure-test the idea against real customers before anything gets built.
Research each idea with hard data — search volume, sales velocity, trend curves, and what actual customers are complaining about.
Part of the idea-consideration process is understanding the distribution / fulfillment model:
Ascertain which is the best idea by using the research and trend tools below; some tools in Hour 1 may still be applicable — the toolset builds each hour. Time to decide on one or two ideas.