I made use of GIMP’s powerful effects like OLD PHOTO and tools such as SMUDGE. The images are dragged on top of a grunge background or two or three from CGTEXTURES which makes layers out of them. The layer mode can then be set to DODGE or BURN or whatever you like. Use the SCALE and MOVE tools to arrange the images.
The photo of me in yukata was “cut out” from the original image by using a layer mask. I forget where I learned about this but if you Google it you can find lots of good tuts like this one.