Which product to make?

I have released products nobody cared about. Hopefully, you can avoid that.

Follow the money and build for the people you understand

Actually, it's simple. Take a good look at some of the products many companies use. Many of these might genuinely suck. They might be ugly, obsolete, hard to use.

By the simple fact of using the latest UI and development standards you can improve a specific process 5x or more. As companies are already spending the money on existing solution, they don't need to justify new item in the budget to use yours instead.

Build for the industry you intimately know

Building something for people in industries you have no contact with is dangerous. You will need to invest a lot of time to learn and truly understand the market.

You need to know how your customers think and where they hang out. You need to be an active person in that community, sharing knowledge. You need to be known and trusted - so when you build something helpful, many will be curious and supportive.

Start small and lean

Do not fall in trap of making a ton of features. Make a product that does one thing really well. If you can't make a good living out of that one thing solved, you have solved the wrong thing.

Bonus point: it's incredibly easy to onboard new customers if you can prove you are either earning them money or saving them money. If so, your product can cost a percentage of that however large that amount turns out to be.