There are several ways to cast on, but this is a less well known method than the popular thumb and cable methods (and if you don't know what your method is called, it's probably one of those two). To be completely invisible it should be used to start a single rib, but I used it with stocking stitch (see photo above) to create a lovely neat decorative edge.
It is not a complicated method - if you can cast on, you can do invisible cast on.
To try it out, you will need:
2 different yarns - the one you will use to create your work and one in a contrasting colour
A pair of needles in the appropriate size for the yarn
Scissors
Step 1
Using the contrast yarn, cast on half the number of stitches you need using your usual method. You must have an even number of stitches and you will end up with an odd number of stitches, double your original count minus 1. So if you start with 10 stitches, you will end with 19.
Step 2
Knit the first row and purl the second row (stocking stitch).
Join the other yarn to the piece and work 3 rows in stocking stitch, ending with the wrong side facing you (so the next row is a purl row).
Purl 1 stitch. Then pick up the first loop of your main colour from where you joined the yarn to the work. Put this loop onto your left needle, take the yarn to the back of the work and knit the stitch.
Purl the next stitch and then pick up the next loop, taking the yarn to the back and knitting as before. Keep doing this until you have picked up all the loops along the row and purl the last stitch.
Step 5
Using your knitting needle or a darning needle, unravel the contrast yarn.

