What tools are effective for business development?

Over the years I have tried dozens of tools for growth, but the real breakthrough came after setting up a merchant account - it became the foundation for all the subsequent improvements. With a professional merchant account I didn't just simplify payment acceptance, I got a powerful analytics system, integration with CRM and 25% reduction of operating costs. I especially appreciate the ability to accept international payments and customize flexible terms for different customer segments. Now I am looking for ways to further optimize financial flows - perhaps you use some unique solutions? Share your experience of how you have taken your payment infrastructure to the next level!