1) Be embedded in the industry for a while
2) Make lots of connections, build credibility
3) Build SaaS app to solve key pain point you experienced in #1
4) Sell to the folks you know from #2
5) For bonus points/de-risking: find 25 potential customers (from #2) and reach out to them and validate this idea (Jobs-to-be-Done). Get a handful of them to commit, even verbally, to buy this when you've got an MVP built.
[1] Clearly this is not the only way to be successful, but "I have a random idea lemme build it" is a great way to be not successful
[2] Succeed = your business that makes enough revenue to support you and a reasonable lifestyle, equating (and/or eventually surpassing) what you would typically make at a W2 gig, from a diversity of customers and not trading your personal time for money.