Marketing Research
I've done volunteer product creation for a handful of startups. The number one problem with the Saas projects I've worked on is this: most operate on the assumption "If you build it they will come". They have no idea whether there will be any demand for their product. The second most common issue is: they have no business plan. How do people with successful products get past this hurdle.
Research the market, the problems and pain points, talk to potential customers, have a plan and be willing to experiment and adapt.