Originally Posted by WIChix

The 301 uses the modern class of needles, Schmetz being one producer. Organ brand are also nice. You can find these on a variety of websites, at your local quilt shop (lqs), and even at nationwide fabric stores.

The important thing is to match the type of fabric to the type of needle. Sharps, or Schmetz microtex, are for woven cottons, quilting cottons, shirting cottons. Ball Point needles are for knit fabrics, like t shirt knits.

Then, you'll want to match size (thickness) of needle for intended purpose and thread size.

For instance, if mending denim jeans, a size 16 needle. For making quilts, an 11 or a 12. I also prefer 11 or 12 for shirtings.

For knits, ball point needles are commonly available in size 14, but I find modern knits generally thinner, and often search for a 12 ball point.

Now, to thread size, I am not well versed. While your 301 can use a size 16 needle, I am not sure if it could handle a matched weight thread in the bobbin case.

But generally, for most household sewing, an all cotton thread in 40 or 50 weight will do just fine, top and bottom.