I have a pet hate - crochet started with a knot, I think it looks untidy so am on a mission to get crocheters using a slip knot to start a project, my not a knot campaign :)
I know there are lots of ways of making a slip knot, this is one of the ones I teach to beginners. There's a video link too

Right handed
http://www.nezumiworld.com/crochet_085.htm

Left handed
http://www.nezumiworld.com/crochet_113.htm