The invisible provisional cast-on is probably the easiest and fastest way to cast on, once you get the hang of it. To start, you’ll need the needle and yarn you are using for your project, and a spare circular needle or smooth waste yarn for holding the provisionally cast on stitches. If you are using waste yarn to hold your stitches, make a slip knot with both yarns held together and place it on the needle. This is only used to hold the yarn in place and doesn’t count as a stitch.
When you are ready to pick up the provisionally cast on stitches, Slip them onto the needle following the path of the waste yarn, then pull out the waste yarn. You will notice that every other stitch is mounted with the right leg to the back of the needle. You will have to turn the stitches the right way around by working into the back loop on the first row.
When worked in stockinette or garter stitch the provisional cast-on is completely invisible. I like to use this cast-on for toe-up socks, top-down hats, and the underarms of top-down sweaters. This is also the same cast-on used for Moebius knitting.