For some of us, we haven't done financial planning work since college and maybe not even then. My best tip is to enlist the help of a colleague in finance. They're expert at this. As I mentioned earlier, you'll want to support your financial planning with some conjoint analysis.
When you look at the Pragmatic Marketing framework, which of these activities must you own and which can be outsourced to others in your company or even other companies? And of those you own, how many can you or should you do with the help of others? Research, financial planning, persona development?
Developing the business of a product is a team sport. Don't go it alone.