Effective item management is crucial. You can purchase knapsack upgrades from Millionaire at Golden Goods to increase your carrying capacity for each item type:

- Basic Knapsack: Holds 12 of each item (Free, starting).
- Large Knapsack: Holds 18 of each item (Cost: 10000L).
- Jumbo Knapsack: Holds 24 of each item (Cost: 30000L).
While items sell back for only a tenth of their price, gems sell for a fifth. This means it's generally more profitable to sell excess gems than common items. Always keep a good stock of recovery items, especially Gumdrops, Chocochomps, Magic Walnuts, and Pep Roots. The 'sparkly' items in your inventory indicate new items you haven't looked at yet. Don't be afraid to use items during tough boss fights; that's what they're for!