some single procedure that can be used to solve all philosophical problems

This is why I keep mentioning transcendental phenomenology. It is for philosophy what string theory is for physics, a strong candidate for the final answer. It's epistemologically deeper than natural science or mathematics, which it treats as specialized forms of rational subjective activity. But it's a difficult subject, which is why I mention it more often than I explain it. To truly teach it, I'd first need to understand, reproduce, and verify all its claims and procedures for myself, which I have not done. But I've seen enough to be impressed. Regardless of whether it is the final answer philosophically, I guarantee that mastering its concepts and terminology is a goal that would take a person philosophically deeper than anything else I could recommend.