The French knot is so much fun and so easy to do. I love this little stitch so much. It is also the main stitch used in candlewick embroidery (which is usually done all in one colour) and it is usually cream candlewick cotton that is used. I have done candlewick embroidery and just love it. I made a huge candlewick piggy of all things...must add a photo of him some time for you all to see.
Anyway, here are the instructions for the French Knot.
First things first. Bring your thread up from underneath your work and wrap your cotton around your needle two, three or even four times, depending on what size French knot you would like to end up with.
The next step is to gently tighten the loops together and place your needle almost straight down into the spot your thread came up from.
Gently hold in place and voila your finished French Knot.