On January 20, 2009, Cemal Ekin made a presentation titled “Don’t Bruise the Pixels: Nondestrucitve Editing Strategies in Photoshop”. The main message was to shoot RAW, use a large color space when importing to Photoshop, and do not push pixels around to edit the image. Layers, blend modes, and blend if sliders offer extremely powerful image editing with exit strategies. You can find the presentation slides on his site but not the actual Photoshop work.