I have applied a warp to an image I am making and it has made the lines look very jagged.
Is there any trick I can do to make these lines look smooth?
I believe the best way to do this is in Illustrator rather than Photoshop. Photoshop is a pixel-based application, which means that each edge of each shape has to be made of pixels, which can look jagged when moved around, as you experienced. Taking the same image and working with it in Illustrator. However, the next problem that you'll run into is that the image you are using is a pixel-image, not a vector. Illustrator solves this by letting you live trace the image, and then expand the appearance to be able to warp the image. But it is going to take some finagling on your part to get it to work. Good luck!