I never had planned on getting chinchillas, but a friend had two with supplies that they wanted to get rid of, and they had nowhere to go so I offered to take them. I spent a week researching as much as humanly possible, so when they came to me with a plastic bottomed cage with plastic shelves, plastic hides and tunnels, etc. I mostly knew what to do. I eventually got them set up in a portion of my FN and got them all wooden levels and such.
I would say my biggest mistake was being completely lost about food and in a pinch when I got them. They came to me with NO food, NO hay, NO dust. I had to go out and buy what I could get at the store. It ended up not being the worst thing ever. I got some oxbow hay, some sort of generic chinchilla food (At least I knew not to get anything with candy bits, etc.), and Blue Cloud Dust.
Even now, I am still learning very much. I've only just now experienced my first chin illness, and going through that has certainly taught me a lot. Seeing everyone's cages and hearing everyone's stories has given me tons of ideas of what is and isn't allowed. (I've been going with the bare minimum, thinking they'd be good. But with Jack's brother's passing, I am trying to keep him very busy and occupied and spoiled.)