You've skipped the most important part of the puzzle: Find something people want to pay you for and do that. Think of all the kinds of software and services that you can provide. Pick 3 that you know for a fact that people will pay for. Investigate those further and try to think of an MVP product or service you could offer and how much it would cost.

I also highly recommend YC's Startup School. It helped my startup enormously. And... watch every episode of Shark Tank; there are lots of free lessons from the sharks who've done this many times before.