These can quickly mount up especially when doing a colourful pattern. They can also get horribly tangled and you can forget which number colour they are (each shade and colour has it's own number; many of the shades are very similar)
Here is a simple way of keeping your threads tidy and remembering their shade number.
Just cut a strip of card (cereal boxes are great for this) then add little cuts down the sides as in the photo. This way you can wrap your left over pieces around the width of the card without them sliding off. Also you can write the shade number above each one. This means that even if you don't use those pieces for this project; you can always find the right number shade again for another project - thus saving you money - and who doesn't love to save money?