Yo what’s up, I use Adobe Illustrator to make my watermarks. There isn’t a correct way to make them,it’s pretty much experimenting with different tools and drawing it out to see what works for you. For mine I just messed around with fonts and see how they went with each other. I also drew the swirly P with the pen tool. A common rule for watermarks is not to make them too big because they can distract the picture, unless it fits with the image itself.