One of my few "don't" rules for myself is -- don't stock up on random, very specific colors of thread and don't be beguiled by the assorted color thread packs. I buy large spools of threads in basic, neutral colors when it is on sale. And if I need a specific color for a project, then I will buy for that project, carefully choosing color and type of thread that will be most appropriate. But I really don't want to mess with the gazillion smaller spools which often aren't quite enough to finish, or that are just the right color but not the best type or weight for the application.
I also don't buy patterns or books unless I intend to make that quilt very soon. Chances are quite high that it will go down in price, not up. And if I don't intend to make that quilt soon, I probably will never make it, because there will be something else that is much more appealing to me later.
I'm another who does not cut scraps smaller. I will remove unusable strands and maybe square up the scrap, and I will press it before storing in a zip lock bag of like colors.
Here's what works for me: I have a bin in which all my zip lock bags of scraps live. When I have too many scraps to fit in there (no stuffing and squashing), I either have to make something with the scraps or get rid of them. Some of my most favorite projects have been from these forced scrap reduction frenzies. See my avatar quilt. I have a pinterest board of very scrap friendly projects in case I run out of spontaneous ideas. I've become kind of known for trademark gift sunglasses cases and zip pouches that are made with a ton of scraps. I've also made wall hangings, table runners, pillows, entire full sized quilts.