| Fuzzy-Wuzzy |
For potions, oils, and ammunition, you just need the Magical Crafting feat and anything that may appear in Crafting Requirements for a particular item.
For scrolls and wands you need to either cast the spell (just once) during the process or have someone else do so in your presence.
Staves generally require one casting each of every listed level of every listed spell in the staff, but that'll be spelled out explicitly in the Casting Requirements for each item.