I've always had a hard time getting a crocheted provisional cast-on to work properly. I have a hard time picking up the stitches right and it never seems to unzip properly.
And then I saw a gal do it a different way on Knitty Gritty (and of course I can't remember who it was or which episode it was) and this way works for me. I haven't found a good explanation of it so this is my attempt at explaining it myself!
Apologies for the one-handed photography, I couldn't figure out a better way to do it. Here goes:
It starts with a crochet chain a couple stitches long, you aren't going to use these, they're just there to anchor the thing.
Grab your knitting needle and hold the chain on one side of it and the working yarn on the other (that's the working yarn kind of hanging behind the needle)
Pull the working yarn around the needle and pull it through making another chain stitch.
And now we have this, that working yarn is now in front of the needle so flip it back around to the other side so it's hanging behind like it was before. Keep doing that until you have the right number of stitches on the needle and Voila:
After the right number of stitches are on there I do a couple chains to anchor the other end too. And now there's a nice neat row of stitches on the needle ready to be used. Yay!