I loved the 2nd Art of Noticing with the prompts. I hope you'll do it with prompts again. (I wasn't sure if it was being replaced with Pieces of Home.)
Hi! I crop/enlarge/adjust and print either from Photos (on my Apple computer) or from Photoshop. In Photoshop you can set the resolution to 300dpi and set constraints on the size you want to crop your image to. You can also use an App like "Print To Size" that can do some of those adjustments for you (I think).