As you begin to sew more with different fabrics, you realize the benefit of using the proper needle. Even if you are predominately a quilter and sew cottons with the Universal needle, there is the occasional clothing alteration that needs your attention. Hemming a silk dress will need a Microtex(Sharp) needle. Making a T-shirt pillow (here) may need a Stretch(Ballpoint) needle.
My favorite discovery has been the Jeans needle together with thread made for jeans. This makes a perfect factory looking hem on jeans. There are many more needles for different needs. There is also a range of sizes as well for each kind. For the Schmetz guide on every needle click here: Schmetz Needle Guide
Now comes the problem with keeping track of all these needles. I keep a needle box. Behind my packages of new needles, I keep index cards for the used needles. This is my system:
Step 1) Begin a new needle. Write an index card with the title being the type of needle and size. Keep this card in front of the others. Write down the projects you make with this needle. It could be several dresses, quilts, etc.
Step 2) When its time to change the needle for a different type of project, remove the old needle and pierce it into the card. Begin a new card for the new needle and repeat Step 1. Always keep the current needle card in front. It will be the only card without a needle.
Step 3) If you break a needle, pierce it into the current card. Fold card several times around needle and tape closed. Throw card away and begin a new needle and a new card.
Through time, you will get in the habit of looking through the used needles before beginning a new needle. You can see how much a needle has been used. If there are a lot of items listed and you are beginning a new large project, you may choose to discard the old needle and begin a new one. If you begin getting skips in your stitches you can refer to the card and see how much you have used it to determine if it is time for a new needle.
I have used this system for many years. I used to put old needles in my pin cushion but I had no idea how old they were. Now as I am getting older, it is too hard to see the tiny size imprinted in the needle also.