Nice. I've been tracing and painting a lot of tile designs recently and it has given me an appreciation for how even quite simple seeming designs have a lot more to them than it seems at first.

Balancing the ratio of space to color, playing with different widths of curves, and choosing an underlying grid - all very subtle but important in producing an interesting symmetrical pattern.

edit : Oh, and also I would recommend this book on tiles : https://www.vam.ac.uk/shop/books/all-books/the-tile-book-157... it has some amazing examples, from many different historical periods and areas of the world.