when i stick my needle in the second stitch i usually give my needles a little pull so that the loop is a little bigger than usual, then i knit it. makes it looser on the right hand needle before you slip the other one over top of it.
also i learned an easy method on this site... http://www.fiberartshop.com/knclbg.htm
...about 3 min and 30 seconds into the cast off video. might want to give that a try too.