Market size, Competition, and Value proposition

Market size: How large is the potential market for your new idea? Put otherwise, how many consumers may be interested? 

Competition: How saturated is the market for similar products? Too much competition can make it extremely difficult to succeed. However, identifying products that have been selling for a while without innovation or improvement could be worthwhile.

Value proposition: Does your new idea offer a benefit that consumers will want to pay for? Amazon reviews can help to identify the benefits that consumers are actively looking for.