Hey, welcome to pixpet :D I do have this pretty comprehensive guide on the inventory that may give you a better idea of what to keep and what to sell: pixpet.net/forum.php?section=post_display&p=30902

it's a lot of text, though.

To answer your question, I do recommend brewing pixpet potions and potions of evolution and second evolution, and baking base evobars and of course evobars for the pet species you want to evolve. Decorative item potions if you want a better chance at bringing home deco to increase slvl.

So from hoards you'll wanna look out for pixeldust, liquid sapphire, liquid pearl and liquid diamond, green and purple mushrooms, any of the 5% rarity special ingredients, jade beads, white dragon scales. Growing Voxel fruits or Trinuts may be helpful

Best fertilizers to keep are the ones that increase fruits, so pumpkin fruit increase and max fruits fertilizers, and plant double and quadruple harvest fertilizers, if not to use then to sell~ The others you can decide for yourself if you need them, otherwise there's no point to saving them up right now.