I have loaded a video to Youtube on how to create them, both from simple fonts and the more complicated cursive scripts. It isn't really that hard, but the process of working while thinking of negatives is something we are not used to. You can see it here
Even I get it wrong sometimes. After making the video I realised I had made an error of omission on one bit! For that reason, I suggest that when you have finished your design, cut it out in a scrap piece of card and then use it - just to check! Normally I scrutinise the file before saving it but in a screen cast I don't have the time to do that!
Once you have got the hang of it, you can make loads of them, the best way to store is in a ring binder with those clear document pages, you can label them so they are easy to find. I cut mine from coloured or clear acetate and they last for ages.