This cast on makes a firm but stretchy edge, but its prime advantage is that it is FAST. It is also very easy to not make it too tight. However, if you still find that your first row is too rigid, cast onto a needle three sizes larger than the pattern calls for or around two needles.
For those that prefer learning from a video, I made you a video tutorial:
(Also see my tutorial for How to Make a Slip Knot.)
Note that the video has you hold your yarn tail over your thumb, the reverse of my instructions. I have tried both ways, and see very little difference. Use the way that seems best to you.
You may want to check out the following pattern:
If this tutorial was helpful to you, please spread the word.