Pick the exact weapon you use and your defense, then check your progress. See where each material drops (monster & quest), whether you exploit the weakness, your next boss with a comfort rating, and stage-appropriate gear & decorations — all connected (saved in your browser).
Sources: quest progression from mhp3rd.net; weapon/armor data derived from mikejsavage/MHP3DB (WTFPL). Weakness/difficulty hints are curated. Data is expanding over time.