I am a hoarder, and of the worst kind (nostalgia hoarder). What I buy, I keep forever. sweatdrop I just can't seem to let go of items that have been part of good memories.
I particularly collect items in certain categories:
~ Birthstone items (except the crowns, which I think look bad with my hair)
~ Magical items, especially sparkles and summoning circles
I used to collect all EIs, but nowadays most don't interest me. I collect MC letters, but I don't always open them into their item contents.
Collecting is on hold these days, though, since I am currently questing Mini Angel Wings. I don't think I can quit buying all new items altogether, especially since this quest is likely to take at least 3 years, but I am trying to be careful and keep most of my funds and efforts directed to this end.
I collect items I think are pretty or otherwise appeal to me, sometimes I will get multiples of them. I always end up buying bit and pieces from the gold shop to finish off a look. I only sell stuff that I don't really like or think I will ever use.
I make avatars or wishlists then I buy everything on them. After that I find them hard to let go for a while, or at least until I do a purge.
When I'm buying from the wishlist I find that even if I decide the item is useless and I don't want it I have to buy it.
I'm OCD D: