The simple cast-on is very fast and easy Cast on method, but tends to make loose stitches that can be hard to work with.
Hold one needle and the end of the yarn in your left hand. With your right hand, take one segment of yarn and turn it clockwise (as you look down on it). Place the resulting loop onto the needle and pull snug. Repeat until all stitches have been cast on.
A common variant uses a slipknot for the first stitch.