Not so much a step-by-step tutorial, but some great tips come to use from Jonah West who posts this 3D matte painting tutorial demonstrating the nuances of creating a matte painting in Photoshop such as blocking in composition, setting a focal point, blocking in lighting and adding finishing details. Jonah then cuts up the Photoshop file and brings the components for projection into Maya and creates a camera move on the matte painting. Check out the final result video below, nice stuff! Read the tutorial here.