Practice will help; I made a mess out of my first 15-20 as well so don't beat yourself up over it. Lots of video's on youtube on how to do it but I think this is one of the most straight forward and clearly filmed. I use this technique on all panfish, not just crappie.
And by the way, that looks like a good eatin' plate! And ragged fillets taste just as good as the picture perfect ones......