I had issues with my first provisional cast on as well. I was trying to follow Amy’s method in her video, but it just wasn’t working for me.
So, I dug out The Knitter’s Book of Finishing Techniques (good reference book!), looked up their instructions on how to do provisional. Viola!!! No more issues here.
So, the long and short of it, and what I did, is this-- crochet a chain a few stitches longer than what your cast on edge should be using waste yarn. After chaining the last stitch, pull yarn through to finish it off, and knot the tail so you know which side to start pulling the chain out… The you just pick up loops through the BACK loops of your chain until you have the required stitches cast on. Later on you can remove the chain when you’re ready to finish off your piece.
You can see an example of this here.
Granted it’s not close up, but it will kind of give you an idea. Hope this helps! Oh yeah, I almost forgot, I made sure that my first stitch cast on was a slip knot, and this was only because I wanted reassurances that my edge wasn’t going to fall apart on me when I went to seem the hem…