Look at the source at all angles" flip vertical, horizontal, 90 degrees ect... Try the polar coordinates, filter distort, polar coordinates" view the results and see if you see anything in there".. think about how you could select part of the picture, like the sky, and put a different sky into it" change picture to black and white, Image, adjustments, channel mixer, (monochromatic). try filter, stylize, find edges" try layer blending modes with different colors, use crop to get various views, look for shapes and features that stand out in the picture and focus on that and see what you can dream up" that's a few ways to get idea's
but most of all, pray to our Holy Spirit for idea's, and supernatural photoshop wisdom from on high! amen.