Is of course one of mine. I buy things for a project in the heat of inspiration, then if I don’t actually do them right away, when I do want to do them, the supplies I need are just dropped wherever instead of organized someplace with all the other stuff I need.
Now there is a thing I want to do, and I have no idea where the things I need are. Grrrr.
Dangerous Crafts for Girls 
And if you buy new supplies, a month after you finish the project, you’ll find three more sets of what you needed. I know that one all too well.
I have boxes and bags and baskets by sorted by project, with labels, even, and a whole notebook of ideas with clipped photos and drawings and notes… And I still can’t get started.