I want to FINALLY unbox my SM Figurarts Zero collectibles, but this is sort of my first time ever collecting. I've seen people display things in glass cabinets from Ikea or use (super overpriced) acrylic boxes for each individual figure.

How necessary/important is it to protect your figures like this and how do you guys display your stuff?

I display my stuff in a glass case, too. It offers a bit of a protection but you can still see all of them displayed properly. I know other collectors keep everything in boxes, but I don't get that. You'd look like you own a shop, not a collection xD You won't be able to see them properly. Upside though reselling will be easy, but I don't plan to ever sell any of my figures so I'm fine with my current setup.

I just display my stuff around the room(if I can).  Some of it is in the drawers and closets because I don't have enough room to display everything I own(even though most of it is small stuff) and I sometimes wear the shirts I own.

The keychains I own are on a corkboard.  I was never able to find Hotaru/Saturn though.

You should keep in mind whether your figures are likely to wind up dusty and if you want to have to dust them. Glass cabinets can really help avoid that kind of accumulation. ♥

My collection is displayed outside of a case, and I just dust it on a regular basis. I haven't had other issues happen (fading, etc.) that would damage the items.

I keep everything boxed away as I can't really display it because of my three cats. But I think a glass cabinet is a great option. I can even be an empty aquarium, you know? At least for the smaller figures.

Displaying your figures in an aquarium that's been set-up to look like a scene from Sailor Moon! (:

Ooooo I like the aquarium idea! Much bigger acrylic box for much cheaper XD. I may go with that! Thank you guys!

I'm kind of curious for an update on what you ended up doing, Sailor Jupiter!

I agree with the NRFB thing making it look like you own a shop. Half of my collection is unboxed and it's definitely the prettiest half haha. Also, despite keeping my old wands in boxes and away from sunlight, some of the plastic that was shown through the cellophane parts of the box still yellowed :'''(. Makes me super sad and now I feel like I can't display those items out of box because they're patchy!