I knit continentally and I had a really hard time learning the purl stitch. I finally got the hang of it about a month ago, and here's my method of it....hope it helps some...
First of all, I wrap the yarn around my pinkie and let it slide my index finger.
Next, I hold the yarn behind the stitch that I'm going to be working with my index finger, to make sure that it stays in place.
I insert my needle into the stitch, backwards from how I would have it for the knit stitch.
Last, I let the yarn "pop" from my index finger, and grab the yarn with my needle.
Hope this helps a little. I've though about making a video of my method, because it took me so long to understand it, and wonder if I could help anyone with the problems that I've had...